In the U.S., 1 in 6 children has an intellectual and/or developmental disability (I/DD). This population experiences a multitude of negative health outcomes across the life course, relative to the general population. Stigma—the social devaluation of individuals with certain characteristics, identities, or statuses within interpersonal, educational, healthcare, and policy contexts—is a potentially preventable contributor to health disparities. To date, existing approaches for addressing and preventing stigma are limited to discrete and siloed interventions that often fail to address the lifelong, cumulative impacts of the specific types of stigma experienced by the I/DD population. In the current paper, we describe three elements of Life Course Health Development (LCHD)—a novel translational framework that draws on evidence from biology, sociology, epidemiology, and psychology—that healthcare providers can use to prevent stigma-related health disparities and improve outcomes for individuals with I//DDs. We discuss the utility of targeting prevention to sensitive periods; prioritizing interventions for the most damaging types of stigmas; and leveraging supports from multiple service systems and sectors. By incorporating evidence from life course science into efforts to address stigma-related health disparities, providers can more effectively and strategically prevent and combat stigma-related health disparities for the I/DD population in childhood and across the life course.