BACKGROUND: Positive Deviance/Hearth (PDH) is an internationally recognized nutrition rehabilitation program. However, nutritional improvements are inconsistent across contexts. It is unclear if variations are due to differences in program design, implementation, utilization, or other contextual factors. Furthermore, few PDH programs have addressed the high time and work burdens of caregivers and volunteers. To address this, the study integrated interactive voice calling (IVC) with PDH. OBJECTIVES: A program impact pathway (PIP) analysis was used to evaluate the secondary outcomes of facilitators, barriers, and contextual factors that influenced the design, implementation, and utilization of a Positive Deviance/Hearth-Interactive Voice Calling program to improve the nutritional status of children in Cambodia. METHODS: A PIP analysis was done on data collected through in-depth interviews with caregivers (n = 32), key informant interviews with volunteers (n = 16) and project staff (n = 3), and surveys of project staff (n = 5). RESULTS: In the design phase, facilitators included quality training, technical support and design tools, community mobilization, and linkage to existing health services. Barriers included poor community mobilization. For the implementation phase, facilitators were good volunteer knowledge, follow-up tools and guidance, supervision, and spot checks of volunteers. Barriers were lack of time and overworked older caregivers. For the utilization phase, facilitators included family and volunteer support and access to phones, whereas barriers were lack of support, time, and financial resources; low levels of education and old age of caregivers; and inconsistent phone use. Contextual factors included food insecurity and increased childcare responsibilities of grandmothers due to migration of mothers. CONCLUSIONS: The PIP analysis identified facilitators, barriers, and contextual factors that may affect the design, intervention, and utilization of IVC interventions for health and nutrition behavior change and elements to consider when designing and implementing them. When implementing child nutrition programs in Cambodia, supporting interventions addressing mental health and time and resource constraints of elderly caregivers should also be included.This trial was registered at clinicaltrials.gov as NCT03399058.