Objective: Acceptance and Commitment Therapy (ACT) is a promising intervention for cancer survivors, but its mechanisms in real-world settings are not fully understood. This study examined ACT-specific and broader target processes as mediators in the Valued Living randomized controlled trial, which compared ACT and usual care for anxious cancer survivors in a real-world community oncology setting.Method: Two ACT-specific target processes (experiential avoidance and values-aligned behavior, each measured with two validated instruments) and two broader target processes (emotional approach coping and self-compassion) were analyzed at Pre- and Post-intervention as predictors and mediators of anxiety symptoms, cancer-related trauma symptoms, and fear of cancer recurrence in a causal steps framework (n = 117). Results: During the intervention, ACT participants improved significantly more than usual care participants on the broader target processes (ps <= .035) but not the ACT-specific target processes (ps >= .080). Cancer-related emotional approach coping mediated cancer-related trauma symptoms and fear of recurrence (ps .043-.044). Self-compassion mediated fear of recurrence (p = .045), and showed marginal patterns for trauma symptoms (p = .059) and anxiety symptoms (p = .084).Conclusion: ACT may work in real-world settings for cancer survivors by promoting self-compassion and coping through emotional processing and expression.