Mapping pathways of how interventions are implemented and utilized enables contextually grounded interpretation of results, differentiates poor design from poor implementation, and identifies factors that might influence the utilization of interventions. Few studies in nutrition have comprehensively examined the steps of implementation and utilization in behavior change communication (BCC) interventions, thus limiting the interpretation of variable impacts of BCC interventions. A program impact pathway (PIP) analysis was used to study a BCC intervention implemented in Bangladesh to improve infant and young child feeding (IYCF) practices. The PIP was developed through an iterative process with the program implementation team; the PIP then guided the choice of methods and tools. Using mixed methods, we reviewed the content of training materials for implementation staff, measured their IYCF knowledge (n = 100), observed their communication with mothers (n = 37), and examined factors influencing promotion of IYCF practices and their trial and adoption by mothers (n = 64). Implementation staff demonstrated good knowledge and maintained fidelity to the intervention to a large extent. Mothers identified them as their primary sources of information, and a majority of mothers tried recommended IYCF practices. Key facilitators included family support and availability of resources, whereas lack of time, maternal and family perceptions of age-appropriate feeding, and lack of resources were salient barriers to adopting recommended practices. Using a PIP analysis identified critical issues pertaining to implementation (e.g., the role of paid and volunteer staff) and utilization (e.g., resource and time constraints that require complementary interventions) and the need for further research and programmatic attention.