 This paper proposes a multi-method approach to understanding the impact of ad hoc modifications on the success of a protocol-driven intervention. The authors use focus groups and semi-structured interviews to understand the protocol as planned by the implementation team, and process maps to capture the actual process as it was implemented in practice. This allows them to identify when modifications occurred during the intervention, which can be used to inform future research into the impact of these changes on the primary outcome. This article was authored by Thomas I, Leah Ramella, Anna J. Schaffer, and others.