Purpose: Individuals recently diagnosed with cancer are commonly asked to make treatment decisions while experiencing acute distress and time pressure. Studying decision-making processes during this time will hopefully provide valuable information to facilitate effective decision-making in the future. However, conducting this research shortly following diagnosis raises significant concerns about the potential for adverse effects on participants. This study explored the psychological impact, safety, and potential benefit of a decision-making study conducted shortly after a breast cancer diagnosis. Method: Following informed consent procedures, women with a recent diagnosis of primary breast cancer were administered the Hospital Anxiety and Depression Scale (HADS). Participants next completed a vignette-based study of adjuvant chemotherapy treatment decisions, an extensive questionnaire battery, and utilities regarding potential chemotherapy effects. Participants were then re-administered the HADS (post-test) as well as individual survey items concerning their reactions to study participation. Results: Participants included 53 women with recently-diagnosed breast cancer. At baseline, only one individual exceeded exclusion criteria for distress and was not offered study participation. Of women who completed the study, 92% described participation as valuable and 78% indicated that it facilitated their decision-making about adjuvant chemotherapy. Additionally, 92% reported the experience was educational and 90% stated they would refer a friend to participate. Paired t-tests revealed that participants experienced a statistically significant decrease in anxiety following study participation (Baseline: M = 7.00 ± 3.87 vs. Post: M = 5.98 ± 4.48), t(49) = 3.42, p = .001. However, depressive symptoms at baseline (M = 3.06 ± 2.71) were unchanged on the post-test (M = 3.34 ± 3.59, t(49) = -1.19, p = .241). Using HADS clinical cut-off scores, analyses showed no significant changes in rates of clinical levels of anxiety and depression immediately following study participation. Conclusions: Overall, participants were not adversely impacted by participating in the decision-making study. In fact, women reported a significant decline in anxiety following participation, and the vast majority of women described participation as valuable, educational, and worth recommending to other women. While data suggest that decision-making research is likely safe and potentially beneficial shortly after breast cancer diagnosis, researchers are cautioned to monitor participants closely and train research assistants to recognize and seek appropriate professional assistance for psychological distress among participants.