Foster parents are the largest group providing care for children in the foster care system. In the course of caring for children who have experienced significant trauma, loss, and uncertainty, foster parents face significant stressors unique to their position. Stress among foster parents can negatively impact the quality of their parenting and, subsequently, the children in their care. However, relatively little is known about those factors which impact foster parent well-being within the context of this stressful role. This study aims to address this gap by examining the relationship between parenting stress and well-being in foster parents, and the potential moderating effect of social support in this relationship. The study utilized a cross-sectional design and web-based survey methodology with a sample of licensed foster parents (both non-relative and relative caregivers) from one county in the midwestern United States. Multiple linear regression analysis indicated that parenting stress is significantly, negatively related to foster parent well-being. Further, social support functions as a moderator, or buffer, in this relationship. Foster parents who indicated higher levels of social support reported being less negatively impacted by parenting stress. While qualitative research has suggested the importance of social support in foster family resilience, this study offers the first known quantitative findings among licensed foster parents on the protective function of social support in the context of parenting stress. These findings have implications for this population and the professionals and systems they encounter, including improved foster parent training and assessment, toward the greater goal of an improved child welfare system for the children within it.