To describe activities and outcomes of a cross-team capacity building strategy that took place over a five-year funding period within the broader context of 12 community-based primary health care (CBPHC) teams. In 2013, the Canadian Institutes of Health Research funded 12 CBPHC Teams (12-Teams) to conduct innovative cross-jurisdictional research to improve the delivery of high-quality CBPHC to Canadians. This signature initiative also aimed to enhance CBPHC research capacity among an interdisciplinary group of trainees, facilitated by a collaboration between a capacity building committee led by senior researchers and a trainee-led working group. After the committee and working group were established, capacity building activities were organized based on needs and interests identified by trainees of the CBPHC Teams. This paper presents a summary of the activities accomplished, as well as the outcomes reported through an online semistructured survey completed by the trainees toward the end of the five-year funding period. This survey was designed to capture the capacity building and mentorship activities that trainees either had experienced or would like to experience in the future. Descriptive and thematic analyses were conducted based on survey responses, and these findings were compared with the existing core competencies in the literature. Since 2013, nine webinars and three online workshops were hosted by trainees and senior researchers, respectively. Many of the CBPHC Teams provided exposure for trainees to innovative methods, CBPHC content, and showcased trainee research. A total of 27 trainees from 10 of the 12-Teams responded to the survey (41.5%). Trainees identified key areas of benefit from their involvement in this initiative: skills training, networking opportunities, and academic productivity. Trainees identified gaps in research and professional skill development, indicating areas for further improvement in capacity building programs, particularly for trainees to play a more active role in their education and preparation.