The following is an inclusive, interfaith calendar of holidays and festivals for 2011. If you have additions or corrections, please leave a comment.
JANUARY
Jan. 1
- Mary, Mother of God (Catholic)
- Feast of St. Basil (Orthodox Christian)
- Gantan-sai - New Years (Shinto)
Jan. 5
- Epiphany Eve (Christian)
- Guru Gobindh Singh birthday (Sikh)
Jan. 6
- Epiphany (Christian)
- Feast of the Theophany (Orthodox Christian)
- Dia de los Reyes (Hispanic Christian)
- Nativity of Christ (Armenian Orthodox Christian)
Jan. 7
- Nativity of Christ (Orthodox Christian)
Jan. 9
- Baptism of the Lord Jesus (Christian)
Jan. 13
- Maghi (Sikh)
Jan. 14
- Makar Sankrant (Hindu)
Jan. 16
- World Religion Day (Baha'i)
Jan. 17
- Blessing of the Animals (Hispanic Catholic Christian)
Jan. 19
- Timkat (Ethiopian Orthodox Christian)
Jan. 19-21
- Mahayana New Year (Buddhist)
Jan. 20
- Tu B'shvat (Jewish)
Jan. 25
- Conversion of Saint Paul (Christian)
FEBRUARY
Feb. 2
- Candlemas (Christian)
- Imbolc - Lughnassad (Wicca/Pagan)
Feb. 3
- Setsubun-sai (Shinto)
- Chinese New Year (Confucian/Taoist/Buddhist)
Feb. 6
- Four Chaplains Sunday (Interfaith)
- Triodion begins (Orthodox Christian)
Feb. 8
- Vasant Panchami (Hindu)
Feb. 14
- Saint Valentine's Day (Christian)
Feb. 15
- Nirvana Day (Buddhism/Jain)
- Mawlid an Nabi - Muhammad's birthday (Islam)
Feb. 18-25
- Week of Prayer for Christian Unity (Christian)
Feb. 20
- Mawlid an Nabi - Muhammad's birthday (Shiite Islam)
Feb. 24
- Saint Matthew, Apostle and Evangelist (Christian)
Feb. 26-March 1
- Ayyám-i-Há - Intercalary Days (Baha'i)
Feb. 27
- Sunday of the Last Judgment (Orthodox Christian)
MARCH
March 1
- Saint David of Wales (Christian)
March 2-20
- Nineteen Day Fast (Baha'i)
March 3
- Maha Shivaratri (Hindu)
March 6
- Cheesefare Sunday (Orthodox Christian)
- Transfiguration Sunday (Christian)
March 7
- Clean Monday - Great Lent begins (Orthodox Christian)
March 8
- Shrove Tuesday (Christian)
March 9
- Ash Wednesday - Lent begins (Christian)
March 13
- Orthodox Sunday (Orthodox Christian)
- Birthday of L. Ron Hubbard (Scientology)
March 17
- St. Patrick's Day (Christian)
- Fast of Esther (Jewish)
March 19
- Magha Puja Day (Buddhist)
- Saint Joseph's Day (Christian)
- Holi (Hindu)
March 20 (Equinox)
- Hola Mohalla (Sikh)
- Holi (Hindu)
- Mabon (Wicca/Pagan southern hemisphere)
- Ostara (Wicca/Pagan northern hemisphere)
- Purim (Jewish)
March 21
- Shushan Purim (Jewish)
- Nowrūz - New Year (Baha'i/Persian/Zoroastrian)
March 25
- Annunciation of the Blessed Virgin Mary (Christian)
March 28
- Khordad Sal - Birth of Prophet Zaranhushtra (Zoroastrian)
APRIL
April 4
- Ugadi - New Year (Hindu)
April 5
- Qingming (Chinese traditional)
April 12
- Ram Navami (Hindu)
- Swaminarayan Jayanti (Hindu)
April 14
- Baisakhi (Sikh)
April 16
- Lazarus Saturday (Orthodox Christian)
April 17
- Palm/Passion Sunday (Christian)
- Mahavir Jayanti (Jain)
April 18-21
- Theravadin New Year (Buddhist)
- Hanuman Jayanti (Hindu)
April 18
- Lord's Evening Meal (Jehovah's Witness)
- Hanuman Jayanti (Hindu)
April 19-26
- Pesach (Passover) (Jewish)
April 19-June 7
- Sefirat HaOmer (Jewish)
April 21
- First Day of Ridvan (Baha'i)
- Maundy Thursday (Christian)
April 22
- Good (Holy) Friday (Christian)
April 23
- Black Saturday (Christian)
- St. George Day (Christian)
April 24
- Easter (Christian)
April 29
- Ninth Day of Ridvan (Baha'i)
April 30
- St. James the Great Day (Orthodox Christian)
MAY
May 1
- Yom HaSho'ah (Jewish)
- Beltane - Samhain (Wicca/Pagan)
May 2
- Twelfth Day of Ridvan (Baha'i)
May 5
- National Day of Prayer (Interfaith USA)
May 9
- Yom Ha'Atzmaut (Jewish)
May 17
- Buddha Day - Visakha Puja (Buddhist)
May 22
- Lag B'Omer (Jewish)
May 23
- Declaration of the Bab (Baha'i)
May 29
- Ascension of Baha'u'llah (Baha'i)
JUNE
June 2
June 8-9
- Shavuot (Jewish)
June 9
- Saint Columba of Iona (Celtic Christian)
June 10
- All Saints (Orthodox Christian)
June 12
- Pentecost (Christian)
June 16
- Guru Arjan Dev martyrdom (Sikh)
June 19
- All Saints (Orthodox Christian)
- New Church Day (Swedenborgian Christian)
- Trinity Sunday (Christian)
- Timkat (Ethiopian Orthodox Christian)
June 21 (Solstice)
- First Nations Day (Canadian Native People)
- Litha (Wicca/Pagan northern hemisphere)
- Yule (Wicca/Pagan southern hemisphere)
June 23
- Corpus Christi (Catholic)
June 28
- Lailat al Miraj (Islam)
June 29
- Saints Peter and Paul (Christian)
JULY
July 1
- Sacred Heart of Jesus (Catholic)
July 9
- Martyrdom of the Bab (Baha'i)
July 11
- Saint Benedict Day (Catholic)
July 15
- Lailat al Bara'ah (Islam)
- Asalha Puja Day (Buddhist)
- Saint Vladimir Day (Christian)
July 13-16
- Ulambana - (Japanese Buddhist)
July 19
- Fast of 17th of Tamuz (Jewish)
July 24
- Pioneer Day (Mormon)
July 23
- Birthday of Emperor Haili Selassi I (Rastafari)
July 25
- St. James the Great Day (Christian)
AUGUST
Aug. 1
- Lammas (Christian)
- Fast in honor of Holy Mother of Lord Jesus (Orthodox Christian)
- Ramadan begins (Islam)
Aug. 2
- Lughnassad - Imbolc (Wicca/Pagan)
Aug. 6
- Transfiguration of the Lord (Orthodox Christian)
Aug. 7
- Laylat al Kadr (Islam)
Aug. 9
- Tisha B'Av - begins at sundown Aug. 8 (Jewish)
Aug. 13
- Raksha Bandhan (Hindu)
Aug. 13-15
- Obon (Shinto)
Aug. 15
- Assumption of Blessed Virgin Mary (Catholic)
- Dormition of the Theotokos (Orthodox Christian)
Aug. 22
- Janmashtami - Krisha Jayanti (Hindu)
Aug. 26
- Lailat al Kadr (Islam)
Aug. 29
- Beheading of John the Baptist (Christian)
Aug. 31
- Eid al Fitr (Islam)
SEPTEMBER
Sept. 1
- Ganesh Chaturthi (Hindu)
- Ecclesiastical New Year (Orthodox Christian)
Sept. 2-10
- Paryushana Parva (Jain)
Sept. 8
- Nativity of Mary (Christian)
Sept. 14
- Elevation of the Life Giving Cross - Holy Cross Day (Christian)
Sept. 23 (Equinox)
- Mabon (Wicca/Pagan northern hemisphere)
- Ostara (Wicca/Pagan southern hemisphere)
Sept. 27
- Meskel (Ethiopian Orthodox Christian)
Sept. 28-Oct. 5
- Navaratri (Hindu)
Sept. 29-30
- Rosh Hashanah - begins at sundown Sept. 28 (Jewish)
Sept. 29
- Michael and All Angels (Christian)
OCTOBER
Oct. 2
- Fast of Gedaliah (Jewish)
Oct. 4
- St. Francis Day (Catholic)
Oct. 5
- Waqf al Arafa - Hajj Day (Islam)
Oct. 6
- Dasera (Hindu)
Oct. 8
- Yom Kippur - begins at sunset Oct. 7 (Jewish)
Oct. 10
- Thanksgiving - Canada (Interfaith)
Oct. 13-19
- Sukkot (Jewish)
Oct. 19
- Hoshanah Rabah (Jewish)
Oct. 20
- Birth of the Báb (Baha'i)
- Shemini Atzeret - begins sundown Oct. 19 (Jewish)
- Installation of Scriptures as Guru Granth (Sikh)
Oct. 21
- Simhat Torah (Jewish)
Oct. 22
- New Year (Jain)
Oct. 24-28
- Deepavali (Hindu)
Oct. 26
- Diwali (Jain/Hindu/Sikh)
Oct. 28
- Milvian Bridge Day (Christian)
Oct. 30
- Reformation Day (Protestant Christian)
Oct. 31
- All Hallows Eve (Christian)
NOVEMBER
Nov. 1
- All Saints' Day (Christian)
- Samhain - Beltane (Wicca/Pagan)
Nov. 2
- All Souls' Day (Catholic)
Nov. 4-7
- Hajj (Islam)
Nov. 6
- Eid al Adha (Islam)
Nov. 10
- Guru Nanak Dev Sahib birthday (Sikh)
Nov. 12
- Birth of Baha'u'llah (Baha'i)
Nov. 15
- Nativity Fast begins through Dec. 24 (Orthodox Christian)
Nov. 20
- Christ the King (Christian)
Nov. 24
- Thanksgiving (Interfaith)
- Gkuru Tegh Bahadur Martyrdom (Sikh)
Nov. 26
- Day of Covenant (Baha'i)
- Al-Hijra - New Year (Islam)
Nov. 27
- First Sunday of Advent (Christian)
Nov. 30
- Saint Andrew's Day (Christian)
DECEMBER
Dec. 5
- Ashura (Islam)
Dec. 6
- Saint Nicholas Day (Christian)
Dec. 8
- Bodhi Day - Rohatsu (Buddhism)
- Immaculate Conception (Catholic)
Dec. 12
- Feast day - Our Lady of Guadalupe (Catholic)
Dec. 16
- Posadas Navidenas (Christian)
Dec. 21-28
- Hanukkah (Jewish)
Dec. 22 solstice
- Yule (Christian)
- Yule (Wicca/Pagan northern hemisphere)
- Litha (Wicca/Pagan southern hemisphere)
Dec. 25
- Christmas (Christian)
- Feast of the Nativity (Orthodox Christian)
Dec. 26
- Zarathosht Diso - Death of Prophet Zarathushtra (Zoroastrian)
- Saint Stephen, Deacon and Martyr (Christian)
Dec. 28
- Holy Innocents (Christian)
Dec. 30
- Feast of the Holy Family (Catholic Christian)
Dec. 31
- Watch Night (Christian)