Background: A growing body of research highlights the experiences of Black men students who successfully navigate science, technology, engineering, and mathematics (STEM) educational pathways. Many Black men graduate students in engineering describe moments when their advisors, peers, and, at times, community members make them feel different because of their race and gender. Needed is a better understanding of what motivates Black men to persist in graduate school despite such challenges. Purpose: This study advances a new theoretical model, "Black Men's Graduate Engineering Motivation" (BMGEM), to describe the overlaying factors and sources of motivation--and their interrelations--that influence Black men in engineering graduate programs to persist. Research Design: To explore the motivational factors that influence Black men in graduate engineering programs at predominantly White institutions (PWIs) to persist, this study of 42 students used an eight-item demographic form, one-on-one semi-structured interviews, and follow-up focus groups. Data analysis was conducted using adapted grounded theory techniques. After the completion of data collection and multiple iterations of analyses (both inductive and deductive), existing conceptualizations of motivation were used to help make sense of data. The connection to existing literature, code development, their placement into categories, and placing categories into themes led to the creation of a substantive, practice-informing theory: Black Men's Graduate Engineering Motivation. Findings: Data analysis resulted in the theory of Black Men's Graduate Engineering Motivation (BMGEM). The BMGEM explains the overlaying factors that influence individuals' experiences and motivations to persist (i.e., sociocultural factors, personal factors, social identities, pre-graduate school experiences), and external and internal motivational sources that also influence students' motivations to persist (i.e., desire to earn a graduate degree, desire to become an engineer, challenges during graduate school, peers, family members, [under]representation, self-coaching practices, career and professional goals). Conclusions and Recommendations: The findings from this study inform future research, and practice-based strategies around broadening participation, that aid in Black men's progress through science and engineering pathways. With this new information, we charge engineering colleges to make true commitments to broadening participation, which means centering students--in this case, Black men--as contributors to STEM. In doing so, engineering colleges need to commit to helping Black men succeed. Assisting in their motivation to persist is a key to meeting this charge.