Background/Context: Studies that compare the achievement benefits of charter public schools versus traditional public schools (TPSs) yield quite uneven results. The quality and long-term commitment of teachers represent related mediators that may help to explain effective and ineffective charter schools. Early findings on the comparative rates of annual turnover-exiting from one's school-appear to show higher turnover in charter schools relative to TPSs. But longitudinal data that allow scholars to track teachers over time remain rare. Little evidence exists on how organizational context may interact with individual teacher characteristics to further explain the propensity to leave one's school. Purpose/Objective: Prior research on teacher turnover focused mostly on whether or not and who leaves. Our research builds on and extends prior studies by investigating not only whether and who but also when a teacher leaves. The phenomenon of our study emphasizes the dynamic nature of teacher exit; namely, we are interested in examining when teachers are at the greatest risk of exiting schools. This dynamic focus marks a departure from the typical teacher turnover analysis in which exit is conceptualized as a status (i.e., exit or not). Population/Participants/Subjects: We used a large sample of elementary (4,788) and secondary teachers (8,467) panel data (from 2002-03 to 2008-09) from the LAUSD. A little over 80% of the teachers in the elementary sample were female, while 61% of the secondary teachers were female. About 40% of the elementary and 47% of the secondary teachers were white. The average years of teaching experience was about two for both elementary and secondary teachers. Special education teachers accounted for 12% of the elementary and 15% of the secondary study sample, respectively. Research Design: We combined event history and multilevel modeling analysis in order to investigate when a teacher exits his or her first assigned school and how organizational membership conditions decision processes at the individual level. Conclusions/Recommendations: The longitudinal and multilevel analysis of teacher turnover supports our theoretical position that organizational dynamics and contextual factors are likely to condition the decision process made at the individual level and thereby influence individual behaviors (i.e., decision to leave a school at certain point in time). This cross-level theoretical perspective adds further support to the argument that focusing on recruiting capable teachers and paying attention to working conditions for long-term staffing stability are aspects of schooling that matter most for student learning, as opposed to a horse-race game (i.e., choice and competition).