Students' early problem behaviors in school can be disruptive and even hinder their learning and long-term success. To prevent and address these problem behaviors, schools across the country report adopting Multi-Tiered Systems of Support for Behavior (MTSS-B). The MTSS-B approach seeks to change the school learning environment by consistently teaching and reinforcing good behavior for all students, and then identifying and providing supplemental supports to students who need it. Given the reported widespread use of MTSS-B but limited evidence of effective programs, "Study of Training in Multi-Tiered Systems of Support for Behavior: Impacts on Elementary School Students' Outcomes," evaluated a promising, intensive program of MTSS-B training and technical assistance. This document provides supporting details on what was evaluated and how the study was carried out including sensitivity analyses for the findings presented in the report. The following four appendices make up this document: (1) The Study's MTSS-B Training and Technical Assistance Program; (2) Study Design, Data Collection, and Analytical Approaches; (3) Supplemental Information on Findings in the Report; and (4) Supplemental Sensitivity Analyses. [For the full report, see ED620900. For the Study Highlights, see ED620901.]