B'More Healthy Community for Kids (BHCK) is an ongoing multi-level intervention to prevent childhood obesity in African-American low-income neighborhoods in Baltimore city, MD. Although previous nutrition interventions involving peer mentoring of youth have been successful, there is a lack of studies evaluating the influence of cross-age peers within interventions targeting youth. This article evaluates the implementation of the BHCK intervention in recreation centers, and describes lessons learned. Sixteen youth leaders delivered bi-weekly, interactive sessions to 10- to 14-y olds. Dose, fidelity and reach are assessed, as is qualitative information regarding what worked well during sessions. Dose is operationalized as the number of interactive sessions, and taste tests, giveaways and handouts per session; fidelity as the number of youth leaders participating in the entire intervention and per session and reach as the number of interactions with the target population. Based on a priori set values, number of interactive sessions was high, and number of taste tests, giveaways and handouts was moderate to high (dose). The number of participating youth leaders was also high (fidelity). Of the 14 planned sessions, the intervention was implemented with high/moderate reach. Data suggest that working with cross-age peers is a promising nutritional intervention for recreation centers.