The technical appendices presented in this document correspond to the synthesis report, "'Who Stays and Who Leaves?' Findings from a Three-Part Study of Teacher Turnover in NYC Middle Schools." The appendices include: (1) Description of Data Source and Samples; (2) Methods; and (3) Who Are the Middle School Teachers in NYC? [The technical appendices were written with the Middle School Teacher Turnover Project: Richard Arum, Jennifer Goldstein, James Kemple, Aaron Pallas, Travis Bristol, Clare Buckley, Amy Scallon, and Barbara Tanner. For the full report, see ED561006.]