This paper presents the lessons learned through a process evaluation (PE) after 1 year of implementation of a 2-year community intervention in Lima, Peru. The intervention consisted of training and motivating community popular opinion leaders (CPOLs) for three marginal population segments to disseminate prevention messages among their peers. PE data included: observations, qualitative interviews with CPOLS, conversations and messages delivered by CPOLs, training facilitators' perceptions about implementation, and a survey of CPOLs. The PE helped to document and enhance the intervention. CPOLs were motivated to talk to their peers. CPOLs perceived that their participation had an effect on their own risk behaviors and saw their role as beneficial to their community. The PE was helpful in examining training delivery and the feasibility and acceptability of the intervention in order to assess the elements related to program success necessary to replicate the CPOL model. © 2006 Elsevier Ltd. All rights reserved.