In California's continuing efforts to improve the quality of public schools, teacher retention is a potentially important strategy. Using a new longitudinal database on public school teachers, the authors examine teacher retention patterns in the state. They investigate the effects on retention of two policies intended to improve retention (teacher induction programs and teacher compensation), as well as the unintended consequences of class-size reduction programs. They also consider the relationship between teacher retention and the shortage of fully credentialed teachers, with a particular focus on high-poverty districts, where the shortage is most severe. (Public Policy Institute of California, February 2006.)