A pilot study was conducted to examine whether Acceptance and Commitment Therapy (ACT) significantly reduced psychological distress, depression, anxiety, intrusive thoughts, and body image concerns, while promoting cognitive defusion (the act of detaching from one’s thoughts and emotions), in a sample of distressed breast cancer patients. Twenty-four women were recruited from the California Cancer Registry. To be eligible to participate, women had to be diagnosed with stage 0 to 3 breast cancer within the past year, demonstrate clinically-elevated levels of distress, as indicated by a score of 13 or higher on the Brief Symptom Inventory-18, have no other history of cancer, agree to be randomly assigned to either the ACT or the attention-control intervention, and be available to attend eight weekly 90-minute sessions. Qualifying participants completed a battery of self-report questionnaires and then were randomly assigned to either the ACT or the attention-control intervention. Participants attended eight weekly 90-minute sessions. After completing the intervention, participants completed the post-intervention (8 weeks), and 3-month follow-up assessments. The assessments included the following measures: Cognitive Fusion questionnaire-13, Hospital Anxiety and Depression Scale, Brief Symptom Inventory-18, Impact of Event Scale-Revised Intrusion Subscale, and the Body Image Scale. Participants were compensated $25 for each assessment. Five 2 (type of intervention) by 3 (time of assessment) mixed model analyses of variance were conducted to examine each outcome. The results indicated that there was no significant interaction for each of the five variables of interest, p > 0.05. There was a significant effect of intervention type for depression scores only. Depression scores were significantly higher in the ACT than in the attention-control group, SNAP (p = 0.04). There was a main effect of time for all five variables of interest. Psychological distress, depressive symptoms, anxiety symptoms, cognitive fusion, intrusive thoughts, and body image concerns significantly decreased from the baseline assessment to the post-assessment and the follow-up assessment ( p < 0.05). The effect of time is notable and suggests that both types of interventions affected symptoms equally. Most past researchers used no-treatment control groups and thus failed to reveal the effects of time. Future researchers should avoid this error.