Kirkham AA, et al. - The objective of this study is to prospectively evaluate adherence to oncologist-referred, exercise programming consistent with current suggestions for cancer survivors among women with early breast cancer across the trajectory of adjuvant treatment. Adherence to supervised exercise delivered in a real-world clinical setting differs among breast cancer patients and across the treatment trajectory. Behavioral strategies and individualization in exercise prescriptions to improve adherence are particularly important for later chemotherapy cycles, after treatment, and for resistance exercise.