This paper describes a mental health capacity-building partnership between the University of Nairobi (UON) and the University of Washington (UW) that was built upon a foundational 30-year HIV/AIDS research training collaboration between the two institutions. With funding from the US National Institute of Mental Health Medical Education Program Initiative (MEPI), UW and UON faculty collaborated to develop and offer a series of workshops in research methods, grant writing, and manuscript publication for UON faculty and postgraduate students committed to mental health research. UON and UW scientists provided ongoing mentorship to UON trainees through Skype and email. Three active thematic research groups emerged that focused on maternal and child mental health, gender-based violence, and HIV-related substance abuse. Challenges to conducting mental health research in Kenya included limited resources to support research activities, heavy teaching responsibilities, clinical duties, and administrative demands on senior faculty, and stigmatization of mental health conditions, treatment, and research within Kenyan society. The partnership yielded a number of accomplishments: a body of published papers and presentations at national and international meetings on Kenyan mental health topics, the institution of systematic mental health data collection in rural clinics, funded research proposals, and a mental health research resource center. We highlight lessons learned for future mental health research capacity-building initiatives.