BACKGROUND: Reducing malnutrition is a key priority for governments in low- and middle-income countries given its lasting effects on child development, health, income, and economic growth. Strategies to improve recommended infant and young child feeding (IYCF) practices, especially during the first two years of life, are considered among the most effective. METHODS: In this paper, we evaluate the long-run impacts of an innovative education strategy based on interactive play and performing arts implemented in El Alto, Bolivia on caregivers IYCF knowledge and practices. Two thousand and fifteen households were randomly assigned to intervention and control groups. Two rounds of data were collected approximately 30 and 42 months after baseline. We estimate short-term (30 month) and longer-term (42 month) intent-to-treat effects using multivariate linear regression analysis, with and without controlling for covariates. RESULTS: The program significantly increased caregiver IYCF knowledge by 0.13 SDs in the short run, and this effect grew over time. The program also improved adherence to recommended IYCF practices by 0.23 standard deviations (SDs) in the short term, but the effect on practices dissipated over time, and no longer-term impacts were detected. Caregivers with above median baseline knowledge, number of children, and age appear to have benefited most from the program. CONCLUSIONS: Our findings suggest that entertainment-education interventions are a promising model for improving and maintaining IYCF knowledge. However, their ability to sustain more permanent changes in IYCF practices is less certain. Further evidence is needed to identify other avenues for producing long-term, sustainable behavior change, especially among indigenous populations in Latin America, where literature on education and behavior-change interventions related to IYCF practices is limited.