The purpose of this brief is to share with researchers and evaluators insights and lessons learned from the Office of Child Care (OCC)-focused evaluation activities conducted throughout the Early Childhood Training and Technical Assistance (T/TA) Cross-System Evaluation project. This project included two primary OCC-focused evaluation activities: 1) evaluating Child Care and Development Fund (CCDF)-oriented peer learning opportunities and 2) evaluating T/TA related to CCDF lead agencies’ Corrective Action Plans. Both activities aimed to examine the relationship between forms of T/TA and specific outcomes of interest. In this brief, we first outline our evaluation questions, review the T/TA system (Child Care TA Network) and key system actors, and describe the administrative data sources and methods used. (author abstract)