Purpose: Single motherhood has been associated with negative health consequences such as depression and cardiovascular disease. Physical activity might reduce these consequences, but little is known about physical activity experiences and beliefs that might inform interventions and programs for single mothers. The present study used social-cognitive theory as a framework to explore physical activity beliefs and experiences among single mothers. Method: Single mothers (N = 14) completed a semistructured interview and the International Physical Activity Questionnaire. Participants were categorized into 3 activity levels, and data were analyzed according to these categories. Results: All participants reported barriers to physical activity. Physically active single mothers seemed to be more confident in their ability to overcome these barriers and more likely to plan physical activity in their daily routine, and they more frequently reported having social support compared with low-active single mothers. Across all activity levels, participants focused on the physical outcomes of physical activity participation such as weight loss. Conclusions: These results provide information that is useful for designing and delivering behavioral interventions for increasing physical activity among single mothers.