BACKGROUND AND METHODS: Physical activity during postpartum is both a recommended and an essential contributor to maternal health. Understanding the beliefs, barriers, and enablers regarding physical activity during the postpartum period can more effectively tailor physical activity interventions. The objective of this study was to document self-reported beliefs, barriers, and enablers to physical activity among a cohort of women queried at 3 and 12 months postpartum. Five questions about beliefs and two open-ended questions about their main barriers and enablers regarding physical activity and exercise were asked of 667 women at 3 months postpartum. Among the sample, 530 women answered the same questions about barriers and enablers to physical activity at 12 months postpartum. RESULTS: Agreement on all five beliefs statements was high (>or=89%), indicating that women thought that exercise and physical activity were appropriate at 3 months postpartum, even if they continued to breastfeed. For the cohort, the most common barriers to physical activity at both 3 and 12 months postpartum were lack of time (47% and 51%, respectively) and issues with child care (26% and 22%, respectively). No barrier changed by more than 5% from 3 to 12 months postpartum. For the cohort, the most common enablers at 3 months postpartum were partner support (16%) and desire to feel better (14%). From 3 to 12 months postpartum, only one enabler changed by >5%; women reported baby reasons (e.g., baby older, healthier, not breastfeeding, more active) more often at 12 months than at 3 months postpartum (32% vs. 10%). Environmental/policy and organizational barriers and enablers were reported less often than intrapersonal or interpersonal barriers at both time points. CONCLUSIONS: A number of barriers and enablers were identified for physical activity, most of which were consistent at 3 and 12 months postpartum. This study provides information to create more successful interventions to help women be physically active postpartum.