With global increases in the population of older adults, there is a critical need for interdisciplinary collaboration to address the complexities of aging. Interdisciplinary research is well suited to facilitate trainee development; this venue provides opportunities for engagement in collaborative projects and networks, positioning trainees to become effective interdisciplinary researchers. This project examined the experiences of graduate students and post-doctoral fellows participating in an interdisciplinary trainee network for research on aging. The methods were informed by principles of reflexivity whereby participants reflected on their experiences of engaging in the network. Key findings included: the contribution of institutions and structures, transcendence of boundaries, and development at the level of the individual and community. Findings highlight the value of investing in trainee development in interdisciplinary collaboration, within and beyond aging research, and can inform the development of interdisciplinary trainee initiatives in other areas of research, policy, and practice.