This paper delves into designing and implementing a process evaluation for a structured pedagogy programme under a Foundational Literacy and Numeracy (FLN) initiative in two central Indian states. The evaluation included 15 classroom observations, 15 in-depth interviews, one focus group discussion with teachers, 9 joint visits and interviews with teacher mentors, and 6 interviews with NGO members per state. By outlining data collection methods and key findings, we emphasise the importance of triangulating information across sources to gain a holistic understanding of the issues. For instance, interviews, school documents, and joint visits revealed that teachers felt unsupported by mentors due to a lack of actionable feedback and demonstrations. Iterative feedback loops during data collection, such as supplementing teacher interviews with findings from classroom observations, highlighted that both teachers and the system prioritised goal achievement over process adherence. Our aim is twofold: to highlight the value of mixed-methods research in evaluating, informing, and scaling educational programs, and to offer practical insights into designing and implementing effective process evaluations.