PURPOSE: The purpose of this study was to determine the efficacy of self-care/self-help promotion and uncertainty management interventions offered by the Self-Help Intervention Project (SHIP) for women receiving chemotherapy, radiation therapy, or hormone therapy for breast cancer. DESCRIPTION OF STUDY: One hundred ninety-three women were randomly assigned either to one of three intervention groups (self- help course, uncertainty management, or self-help course plus uncertainty management) or to a control group. Data were analyzed by a repeated measures multivariate analysis of variance procedure using a two-level blocking factor (high and low resourcefulness) and four outcome variables (self-care, self-help, psychological adjustment, and confidence in cancer knowledge). Data were collected at baseline (T1), which was after initiation of adjuvant therapy, allowing for the emergence of treatment-related side effects; 6 to 8 weeks after T1 (T2); and 3 months after T2 (T3). RESULTS: At baseline, women having high resourcefulness compared with women having low resourcefulness evidenced greater self-care, self-help, psychological adjustment, and confidence in cancer knowledge. Participation in SHIP interventions resulted in higher levels of self-care, self-help, psychological adjustment, and confidence in cancer knowledge by time effect in a significant number of women regardless of their baseline resourcefulness. Women participating in SHIP interventions who had low baseline resourcefulness demonstrated the greatest change over time in the outcome variables. Post hoc results indicated that the effect primarily was the result of changes in psychological adjustment, confidence in cancer knowledge, and self-care. CLINICAL IMPLICATIONS: The findings of this study address both the treatment effect for supportive care interventions and the needs that have emerged from review of the last 20 years of supportive care research. Some SHIP interventions evidenced more strength than others; data indicated that large percentages of women with low resourcefulness who received no SHIP interventions experienced a decrement in self-care, self-help, confidence in cancer knowledge, and psychological adjustment over the time that they received adjuvant therapy. Women's level of confidence in their knowledge about cancer being sufficient for self-management and self-help activities was not linked to baseline resourcefulness level. Thus, inherent resourcefulness was not a factor in need for supportive services that could maintain or increase confidence in cancer knowledge usefulness for self-management and self-help. Healthcare providers should note that although the women with low resourcefulness benefited the most from the interventions, women who evidenced high resourcefulness at baseline reported the same level of need for confidence in cancer knowledge and for self-help.