This case study describes a research project employing a sequential explanatory mixed-methods design investigating teachers' motivations, expectations, values, and teaching practices due to their attendance of an innovative Professional Development program in the United States. The Professional Development program, called Research Experience for Teachers, is based on a cognitive apprenticeship model which supports teachers' active learning in an authentic context and uses inquiry-based learning strategies. Specific methodological problems arose in the course of the research. The case study describes particular challenges in carrying out a research study designed around the Professional Development program's features and issues related to study design, measures, and data collection capturing participants' retrospective accounts of their Professional Development experiences. [This content is provided in the format of an e-book.]