The purpose of this study among breast cancer survivors is three-fold: (i) to evaluate the efficacy of the MBSR(BC) program in improving psychological and physical symptoms, quality of life and measures of immune function and a stress hormone (cortisol); (ii) to test whether positive effects achieved from the MBSR(BC) program are mediated through changes in mindfulness and fear of recurrence of breast cancer; and (iii) to evaluate whether positive effects achieved from the MBSR(BC) program are modified by specific patient characteristics measured at baseline.