Putting three generations under one roof--the most common multigenerational living arrangement--became a growth industry during the recession. As the economy and housing markets steadily if slowly recover, the financial stresses driving this trend will recede. However, the personal and social benefits of expanded living arrangements can be enormously positive lifestyle developments for some families, particularly in an aging society.

Before World War II, about 25 percent of Americans lived in multigenerational households. After the war, rising affluence and a mobile society led to a steady decline. "In 2008, an estimated 49 million Americans, or 16 percent of the total U.S. population, lived in a family household that contained at least two adult generations or a grandparent and at least one other generation," according to the Pew Research Center. "In 1980, this figure was just 28 million, or 12 percent of the population."

"Back in the 1940s and 1950s, the common advice was to cut what was called 'the silver cord,'" says Stephanie Coontz, a professor of history and family studies at The Evergreen State College in Olympia, Wash. "Don't take your parents in, experts warned. Don't even remain very close to them. Focus on your own nuclear families."

"Those years were the low point in all of American history in the percentage of multigenerational households, as well as in favorable attitudes toward them," adds Coontz, who also works with the nonprofit Council on Contemporary Families. "I think that there has been a rediscovery of the importance of intergenerational ties in recent years, partly perhaps because marriages have become more fragile, partly because adult kids often delay marriage long enough so that they socialize more with their parents in their 20s, and partly because more democratic and individualized child-rearing values have led to a greater sense of closeness."

Viewed from the perspective of the oldest generation, living in multigenerational homes requires a lot of compromises and adjustments, experts say.

"The most important thing is for people to be able and willing to communicate what they want, what they're willing to do, and what they're not willing to do," says Joshua Coleman, a private psychologist who specializes in adult child-parent relationships. There also needs to be joint recognition that when such households are formed, there is usually a power imbalance.

[Read: 6 Fun Ways to Teach Kids About Money.]

The owners of the home tend to have the stronger position of control. "The person whose home is being moved into may be a little bit more set in their ways of how they want the household to run," Coleman says.

If the adult child has lost his or her job, guilt and shame may be brought into the equation. If an older parent has chronic health problems that require substantial care, this can create its own type of imbalance in the relationship. Imbalances also can be a major source of stressful conflict in money issues. Even if respective financial responsibilities have been agreed to in advance, those shouldering most of the financial burden may have, or feel they deserve, a controlling role in the household.

"Ideally, it's a negotiation among equals where everyone's feelings are taken into consideration," Coleman says. "But that requires people to communicate, and a lot of people aren't very good communicators." He emphasizes that the best time to communicate is before generations move in together. "It's always easier to brainstorm potential conflicts beforehand then to try to create new rules or boundaries afterwards."

"One of the tensions seems to be over each generation's love life," Coontz says she has observed in her research. "I expected, of course, that the parents would have to come to terms with their children's romantic and sexual entanglements. But I've heard of several instances in which the younger generation living with a single mom or dad has gotten judgmental about his or her dating choices."

Other situations requiring special attention include conflicts between grandparents and their adult children about grandchildren. Generational parenting attitudes often differ, and grandparents may need to step back and refrain from imposing their own parenting views on their children. Also, grandparents should not be the assumed to be sitters, available on little or no advance notice to care for grandchildren.

Lastly, Coleman notes, sensitivity is required when key family members are not blood relatives of other household occupants. It might be an in-law spouse or even the friend of a teen or young adult grandchild. Do not assume they will have the same attitudes toward multigenerational living as do direct family members.

[Read: Should Seniors Live Alone or With Family?]

AARP has developed a nine-point checklist to help families--and older family members in particular--achieve success:

1. Prepare your home. Does your home work for everyone, young and old? Can your house accommodate someone who might find climbing stairs a challenge or who might need a walk-in shower or a single-handle faucet?

2. Prepare your family. Have regular family conferences to discuss issues before they become problems. Before moving in together, ask family members of all ages to talk about how they expect life to change, including what they want, what they are excited about, and what they're nervous about.

3. A place for everyone and everyone in their place. Decide how the living space in your home will be used.

4. Let them live their own lives. This is important whether older household members are highly active and independent or if they are being cared for. Opportunities to see friends, continue activities they enjoy, and have downtime are important at any age.

5. Get in a groove. Consistency will help minimize the inevitable disruptions. Keep routines such as mealtimes and bedtime rituals.

6. Make a play date. Facilitate grandparent-grandchild interactions.

[Read: How to Help Family Members Without Hurting Your Own Finances.]

7. Don't get caught in the middle. Often, parents have trouble trying to please the older and younger generations. You can't be expected to take care of everyone if you are running on empty.

8. Be realistic. Only so much furniture can fit in a house. People can only be expected to change so much over a lifetime. Teens will want to hang out with their grandparents only so much. Elders will be willing to handle only a certain volume level on the stereo. There are only 24 hours in a day. And you can be in only one place at a time, no matter how much everyone needs you.

9. Make memories. Capitalize on the opportunities you have with multiple generations in the household. Have fun and treasure the time.

Read more on U.S. News
Working Longer: Still the Best Path to a Better Retirement
How Healthcare Spending May Derail Your Retirement
AARP Maps Fight to Rebuild Middle Class

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  • Boston

    Romance, as we age, blossoms from ever deeper wells of the soul. True, probably, but it helps to have a charming, waterfront city to help get things rolling. <a href="http://www.aarp.org/home-family/livable-communities/info-06-2012/great-cities-for-older-singles.3.html" target="_hplink">Boston</a> manages to meld scrappy and intellectual -- a relatively small city that is home to some of the most prestigious universities in the world, bolstered by culture, parks and a fine quality of life. Greater Boston (population 4.5 million) includes the city of Boston (617,594) and more than 100 cities and towns. The smaller places range from 17th-century villages (Plymouth) to some of the oldest suburbs in America (Brookline and Braintree). Many area towns were built in the 18th century and most feature central squares surrounded by small businesses and residential neighborhoods. In 2011, Boston was ranked the fifth most literate big city in the United States, and a high share of area residents have a college degree. The city's parks are big and exceptionally good, with several designed by Frederick Law Olmsted. The Arnold Arboretum at Harvard is one of the finest in the world. The Massachusetts Audubon Society's Boston Nature Center has opened on the grounds of the old Boston State Hospital. The metro area also offers nearly 120 miles of Atlantic coastline and lots of dedicated bike paths. Locals bond over sports: The Red Sox and New England Patriots have become regular contenders; the Celtics are synonymous with Boston hoops tradition; and the Bruins have the second-most Stanley Cup victories by a U.S. team in NHL history. Massachusetts is a great place to be retired from a government job or the military because most payments from public pensions are exempt from state taxes. And metro Boston is a major center of medical talent, with a very high concentration of physicians, hospital beds per capita and teaching hospitals. Rates of smoking and obesity are low, so the metro area has low mortality from heart disease and low rates of hypertension. Because traffic congestion is a serious problem in the city, many locals use the region's excellent subway system or walk or bicycle to work. Boston's coastal location means it does get severe storms, including nor'easters, blizzards and the occasional hurricane. That's when it's time to curl up on the couch with that special someone and watch the weather roll in.

  • Milwaukee

    <a href="http://www.aarp.org/home-family/livable-communities/info-06-2012/great-cities-for-older-singles.11.html" target="_hplink">Milwaukee</a> is like Philadelphia with some of the rough edges sanded down -- a manageably sized city populated by fun-loving locals, with a dollop of Midwestern wholesomeness stirred in for good measure. But Milwaukee isn't lacking excitement: The city has matured nicely since the days when breweries and manufacturing ruled, with smart riverfront development and a slate of things to do to quench most tastes. Milwaukee is a collection of villages. A historic district packed with trendy shops and cafes on Brady Street is just a few miles south of Harambee, an up-and-coming African American neighborhood whose name means "let's all pull together" in Swahili. Once the sun sets, older singles tend to steer away from the youthful exuberance of downtown for more, um, demographically friendly venues like Kiko's on West Bluemound Road, where live bands fuel the dancing on weekends, or one of the dozens of corner bars dotting Milwaukee's neighborhoods. This metro area of 1.75 million covers four counties in southeastern Wisconsin. The center of Milwaukee (population 594,833) hugs Lake Michigan about 80 miles north of Chicago. As the local economy has been forced to relinquish its reliance on manufacturing, most job growth now occurs in services and health care. Thanks to its excellent public schools and unusually large number of higher educational institutions, Milwaukee enjoys a well-educated labor force. The largest schools are the University of Wisconsin-Milwaukee (enrollment 30,000) and Marquette University (11,000). The city also has a large and well-funded public library system. The extensive local and regional transit systems offer connections to Chicago and Minneapolis. The many miles of Lake Michigan coastline provide oodles of recreation opportunities. Milwaukee's French and German heritage helps explain its tradition of supporting classical music. A Beethoven Society was founded even before the city was incorporated, and the local symphony maintains an active schedule. The city has a large theater district and multiple museums, including the striking wing-shaped Milwaukee Art Museum (designed by Santiago Calatrava) and Harley-Davidson Museum. The concentration of physicians and specialists is high, but so are rates of obesity and diabetes. But the people here are comfortable with themselves, and that makes it easy to find good conversation and dance partners.

  • San Francisco

    In the 1960s and '70s,<a href="http://www.aarp.org/home-family/livable-communities/info-06-2012/great-cities-for-older-singles.2.html" target="_hplink"> San Francisco</a> achieved mythical status as the land of free love. Fast-forward 40 years: Social mores have changed, but San Francisco still reigns as a bastion of active dating across all demographics. It helps, of course, that the city has a fairly compact center loaded with date-friendly diversions -- indoors and out -- to suit most tastes. Maybe it is the mix of nature's wonders and cosmopolitan allure that sparks romance: Whether you are strolling the wharfs, huffing up one of the city's vertiginous hills, sampling sushi in the Noe Valley neighborhood or cycling across the Golden Gate Bridge, San Francisco seems to shine -- at least when it's not blanketed in fog. San Francisco is among the top 10 metro areas for population density, with more than 800,000 people packed into a central city the size of Disney World. The city has a diverse and tolerant population, with a strong gay and lesbian community and more than 100 distinct neighborhoods. S.F. is well known for its eccentricities, but it is also a high-functioning city. In 2010, Foreign Policy magazine ranked San Francisco as the world's 12th most important city. San Francisco also ranked ninth on the 2011 list of America's Most Literate Cities. The job market is holding up better than it is in most cities, and foreclosures are much less of a problem than they are elsewhere in California. Although traffic congestion and commute times are bad in San Francisco, driving is often optional. Bay Area Rapid Transit (BART) anchors one of the most efficient regional transit systems in the United States, and the system continues to grow. Both San Francisco and its huge woodsy park, the Presidio, have been honored as bicycle-friendly locales. San Francisco's universities are yet one more place for older singles to meet up. San Francisco State University has an Osher Lifelong Learning Institute. The University of California, San Francisco, is exclusively devoted to health and medical education, which contributes to a high number of physicians per capita. The region is also an extremely healthy place to live. The metro area has a high proportion of population age 65 and older, and the age-adjusted health status of that population is among the best in the United States.

  • Pittsburgh

    Perhaps as much as any city in the United States, <a href="http://www.aarp.org/home-family/livable-communities/info-06-2012/great-cities-for-older-singles.10.html" target="_hplink">Pittsburgh</a> has leapfrogged into the 21st century, remaking itself from a dying, dirty steel town to a lively, clean beacon of the new economy, awash in cutting-edge culture, dining and entertainment. But enough vestiges of the old days remain, including iconic bridges and signature buildings, to make Pittsburgh feel pleasantly gritty. The only downside for older singles is that the city proper is getting younger -- the percentage of the population age 65 and older dropped to 13.8 percent in the 2010 census. But at 16.8 percent, Allegheny County remains among the top in the country for percentage of seniors over age 65. In the new 'Burgh, you can enjoy a fine meal of locally sourced ingredients at Douglass Dick's Bona Terra restaurant, drink award-winning craft beer at the Church Brew Works, and take in the ballet at the Benedum Center or an art-house movie at the Harris Theater. Or you could have a Primanti Brothers sandwich topped with fries before hitting Jack's Bar on the Southside for $1.25 beer specials -- and possible off-the-ice sightings of Penguins hockey players. Pittsburgh's economy has successfully diversified to include biotechnology, health care and software. The new Pittsburgh is smarter and cleaner. Indeed, you can once again catch fish in the Monongahela River. Unemployment is much lower than the national average; likewise, the foreclosure rate is among the lowest in the country. Pennsylvania is also a prime place to live on a pension: All money withdrawn from pensions is exempt from state taxes. Several large research universities have helped drive Pittsburgh forward. Chief among these are Carnegie Mellon University (enrollment 12,000) and Duquesne University ( 10,300), which -- along with the University of Pittsburgh's main campus ( 28,766 ) -- have spun off businesses from their research contracts. Pittsburgh also claims a rich tradition of philanthropy: Andrew Carnegie lived (and gave) here, and today the Heinz family maintains a $1.7 billion foundation focused exclusively on southwest Pennsylvania. Allegheny County's libraries function as crucial community centers. Those libraries, represented by the Allegheny County Library Association, recently joined with AARP and the Highmark Blue Cross Blue Shield PALS (People Able to Lend Support) program to organize walking groups for adults age 50-plus. The region has above-average outdoor recreation -- mountains, rivers and trails abound -- and below-average rates of cancer, heart disease and other chronic health problems. Despite all the change, residents still abide by a sense of community drawn from their immigrant roots, and that makes for an inviting place to be regardless of your relationship status.

  • St. Louis

    Two hundred years ago, <a href="http://www.aarp.org/home-family/livable-communities/info-06-2012/great-cities-for-older-singles.6.html" target="_hplink">St. Louis</a> was the last place Lewis and Clark could buy gunpowder before paddling into the Wild West. Today, it has grown into the 15th largest metropolitan area in the country. But while it's matured, the city still has a wild edge reminiscent of the frontier days. St. Louis contains more than six dozen neighborhoods, each with its own character. Some are more conducive to mingling than others. The Central West End is home to galleries and antiques shops, sidewalk cafes and bars. As the website Explore St. Louis says, the neighborhood is "a little European, a little New York and totally St. Louis." It also boasts the Cathedral Basilica of Saint Louis, which has the world's largest collection of mosaic art. The St. Louis metro area (population 2.8 million) includes eight counties in Missouri and eight in Illinois. Lots of nice suburbs lie to the north and west in St. Charles County: three of these, St. Peters (55,000), O'Fallon (75,000) and St. Charles (64,000), made the list of best 100 small cities in a 2008 study by Money magazine. St. Louis is one of America's "most livable communities," according to Partners for Livable Communities, with lots of walkable places. The American Planning Association recently honored the Delmar Loop in University City as one of the 10 Great Streets in America, and the warehouse buildings downtown have recently been remade into glitzy residential lofts. There are also village-style developments out in the suburbs, such as WingHaven in O'Fallon, New Town at St. Charles and Park Plaza in Edwardsville, Ill. The metro has more than 30 degree-granting institutions, including several community college campuses and seven schools with enrollments of more than 10,000. Washington University and Webster University are private colleges; the University of Missouri, St. Louis, and Southern Illinois University Edwardsville are public; and Saint Louis University is a Jesuit college. Nature lovers bask in the city's 105 parks. The jewel of the system is Forest Park, the 1,293-acre site of the 1904 World's Fair and now home to the city's sublime zoo and first-class museums of art, history and science. Forest Park also harbors the Municipal Opera, golf courses, tennis courts, baseball diamonds, and facilities for bicycling, boating, fishing, handball, ice skating and more. Powell Hall, home of the renowned St. Louis Symphony, is a few blocks away from Forest Park. The neoclassical Central Library building anchors a large library system. And Union Station, built in 1892, reopened in 1985 as a hotel, shopping and entertainment complex, and is now a major attraction. Downsides include bad air pollution and humid summers. But a mug of local beer in an air-conditioned bar or sidewalk cafe can ease both of those ills.