Hung-Hsi Wu is Professor of Mathematics Emeritus at the University of California at Berkeley where he taught from 1965 to 2009. He got into mathematics education in 1992 in response to his observation of obvious problems in the teaching of mathematics in schools, including the school mathematics curriculum, textbooks, assessment, and professional development. He worked with the State of California in 1997-2005 in all aspect of mathematics education. Since 2000, he has given summer professional development institutes every year for elementary and middle school teachers within the U.S. and abroad. He was on NAEP's Mathematics Steering Committee, 2000-2001, that contributed to the revision of the NAEP Framework, the National Research Council Mathematics Study Panel that wrote the volume "Adding It Up," and also the National Mathematics Advisory Panel in 2006-2008. He is currently serving on the TIMSS 2011 Science and Mathematics Item Review Committee. His main effort in recent years has been directed at the writing of several textbooks for professional development of K-12 mathematics teachers. His articles on mathematics education can be accessed from his homepage.