This mixed methods research study utilized a QUAL→quan design to discover best practices for the evaluation of teacher professional development within a collaborative model. The study also identified enabling factors and barriers to the evaluation of collaborative styles of professional development. The research study was organized using Stufflebeam's CIPP model (Stufflebeam, 1983). A qualitative questionnaire was created by the researcher based on emergent themes and patterns from observational data collected during ongoing collaborative professional development (PD) activity. The questionnaire items were organized by Guskey's five critical levels of PD evaluation model (2005) to form a quantitative questionnaire. The quantitative findings suggest teachers viewed the collaborative style of professional development as a positive experience that benefited students' performance. This research study demonstrated a framework for evaluating teacher performance resulting from participation in a collaborative style of professional development (PD).