Background: African-Americans (AA) and lower socioeconomic status (SES) older breast cancer survivors (BCS) are more likely to experience poor functional and health outcomes. Promotion of healthy behaviors, such as physical activity (PA), is critical to addressing these health disparities. Here we describe the rationale, design and methods of a randomized controlled trial testing the effectiveness of a physical activity intervention among older BCS from diverse racial and SES backgrounds. Methods: The IMPROVE Study is a community-based randomized-controlled trial designed to recruit 320 BCS, 80 in each of four strata defined by race (AA vs. Non-Hispanic Whites [NHW]) and SES (low vs. high). Participants are aged ≥ 65 years, AA or NHW and are within five years from treatment completion for stage I-III breast cancer. Participants are recruited utilizing the Ohio Cancer Incidence and Surveillance System database or directly from three area hospitals in Cleveland, Ohio and randomized to one of two arms: a 52-week moderate intensity aerobic and resistance group training intervention (n = 160) versus attention-control (support group sessions), (n = 160). The first 20 weeks of the PA intervention includes 3x per week 60-minute supervised sessions. The last 32 weeks of the PA intervention are unsupervised. Each of the 60-minute supervised PA sessions include 30 minutes of moderate intensity aerobic activity at 50%-70% of HRmax (maximum heart rate) and 30 minutes of resistance training based on 1-RM (repetition maximum) for chest and leg press. The attention-control group attend a once per week 60-minute support group session for the first 20 weeks and have unsupervised group sessions during the last 32 weeks. Exit interviews are being conducted at 52 weeks. The primary outcome is change in Short Physical Performance Battery (SPPB) Scores at 20 weeks. Secondary outcomes include change in SPPB scores at 52 weeks, and change in body composition and biomarkers of breast cancer prognosis at 20 and 52 weeks. One hundred and seventy-four participants have been enrolled as of 02/07/2019. Discussion: This study includes three underserved populations, (older BCS in general, older AA BCS and older low SES BCS) in one study. Results may contribute to a better understanding of factors associated with recruitment, sustained participation and acceptability, and will inform physical activity programs that will optimally improve the functional and health outcomes for older women during breast cancer survivorship. Clinical trial information: CNCT02763228.