Underserved populations, including racial/ethnic minorities, individuals with low socioeconomic status, and individuals with physical disabilities, are less likely to engage in sufficient moderate to vigorous physical activity (MVPA) and are thus at increased risk of morbidity and mortality. These populations face unique challenges to engaging in MVPA. Learning how to overcome these challenges is a necessary first step in achieving health equity through health promotion research. In this review of the literature, we discuss issues and strategies that have been used to promote MVPA among individuals from underserved populations, focusing on recruitment, intervention delivery, and the use of technology in interventions. Physical activity promotion research among these vulnerable populations is scarce. Nevertheless, there is preliminary evidence of efficacy in the use of certain recruitment and intervention strategies including tailoring, cultural adaptation, incorporation of new technologies, and multilevel and community-based approaches for physical activity promotion among different underserved populations.