One in seven women will develop breast cancer. Most will suffer medically and psychologically from the disease. Complementary and alternative medicine (CAM) interventions such as tai chi and spiritual growth groups have proven to be beneficial for this population, however, many questions remain regarding the mechanisms of action in these techniques. The purpose of this study was to evaluate the psychosocial effects and mechanisms of two 10-week interventions (tai chi and spiritual growth groups) within the context of a larger randomized, controlled NCI-funded study (R01 CA114718, Nancy McCain, PI) in women recently diagnosed with breast cancer. The present study evaluated dispositional predictors (optimism, attentional style, emotional intelligence) as well as the effects of these interventions on measures of mood, coping, and quality of life (QOL) in a subsample of 40 women enrolled in the larger study. Participants were primarily Caucasian (73%) with a mean age of 49 years. Data were collected just prior to beginning chemotherapy when the interventions began, and again 10 weeks later. Twenty-nine participants completed the interventions and had both time 1 and time 2 data. There were 15 women in the tai chi group, 6 in the spiritual growth group, and 8 in the control group. Results from this subsample revealed differential effects of the interventions on total mood disturbance, depressive symptoms and QOL. Optimism was a significant predictor of TNF-α levels, monitoring was a significant predictor of changes in anxiety and QOL, and emotional intelligence was a significant predictor of changes in QOL. These findings give promise to future studies aimed at cross-validating with a larger sample. This research could potentially guide the treatment of women with breast cancer by providing enhanced understanding of how tai chi and spiritual growth groups affect this population psychologically, behaviorally, and biologically.