Women treated with chest radiation for a pediatric cancer have low mammography screening rates despite their high risk for breast cancer. This study characterized the relationship between perceptions of mammography and screening practices. A cross-sectional survey was administered to 523 women in North America who were treated with chest radiation before 21 years of age. Women with inconsistent mammography perceptions and practices were identified using the Pros and Cons of Mammography for perceptions and Transtheoretical Model stages of adoption for prior and intended screening practices. Classification and regression tree (CART) analysis was used to identify barriers to and facilitators of screening among women with positive and negative perceptions. Nearly one-third of the cohort had inconsistent perceptions and practices: 37.4% had positive perceptions and were not having mammograms; 27.6% had negative/neutral perceptions and were having mammograms. Regardless of perceptions, a recent physician's recommendation for mammography, age ≥ 40, and interest in routine health care were universally associated with mammography practices. For women with positive perceptions and a physician's recommendation, barriers to screening included high acceptance coping, low active-planning coping, and high internal health locus of control. For women with negative perceptions, acknowledging the importance of asymptomatic screening was associated with mammography.