Background Comparative effectiveness research (CER) is supported by policymakers as a way to provide service providers and patients with evidence‐based information to make better health‐care decisions and ultimately improve services for patients. However, Latina/o patients are rarely involved as study advisors, and there is a lack of documentation on how their voices contribute to the research process when they are included as collaborators. Objectives The purpose of this article was to contribute to the literature by presenting concrete contributions of Latina/o parent involvement to study design, implementation and outcomes in the context of a CER study called Padres Efectivos (Parent Activation). Methods Researchers facilitated a collaborative relationship with parents by establishing a mentor parent group. The contributions of parent involvement in the following stages of the research process are described: (i) proposal development, (ii) implementation of protocols, (iii) analysis plan and (iv) dissemination of results. Results Mentor parents’ contributions helped tailor the content of the intervention to their needs during proposal, increased recruitment, validated the main outcome measure and added two important outcome measures, emphasized the importance of controlling for novice treatment status and developed innovative dissemination strategies. Conclusions Mentor parents’ guidance to the researchers has contributed to reaching recruitment goals, strengthened the study protocol, expanded findings, supported broad ownership of study implications and enriched the overall study data collection efforts. These findings can inform future research efforts seeking an active Latino parent collaboration and the timely incorporation of parent voices in each phase of the research process.