The four appendices in this report accompany the full report "The Effects of a Principal Professional Development Program Focused on Instructional Leadership. NCEE 2020-0002," (ED599489). They include: (1) The Study's Principal Professional Development Program; (2) Study Design, Data Collection, and Analytic Methods; (3) Supplemental Tables; and (4) Interpreting Study Findings: Alternatives to P-Values and Statistical Significance. [For the study highlights to this report, "The Effects of a Principal Professional Development Program Focused on Instructional Leadership. Study Highlights. NCEE 2020-0002," see ED599490.]