Brief and single-symptom forms of cognitive behaviour therapy (CBT) for distressing voices may increase access to evidence-based psychological therapy and transcend diagnostic barriers. The current study evaluated the "C" and "B" in CBT for distressing voices in a transdiagnostic voices clinic. The B module (component of therapy) sought to enhance coping with voices, and the C module evaluated the accuracy of negative beliefs about the self and voices. The aims of the study were to investigate (a) whether modules B and/or C led to significant and clinically meaningful improvements on the primary outcome of voice-related distress, and (b) if changes in beliefs about self and voices (proposed change mechanisms) underpinned changes in voice distress across module C. Each module consisted of four sessions, individually tailored yet manualized, and designed with ease of staff training and delivery in mind. Assessment measures were administered at baseline (T1), post-module B (T2), and post-module C (T3). The results (N = 62) showed statistically significant medium-sized pre- and post-effects for voice-related distress from T1 to T2 and from T2 to T3, with large effects from T1 to T3. Just over half of the clients reported clinically meaningful improvements from T1 to T3. Neither beliefs about self nor voices were found to mediate improvements in voice distress during module C. The findings from this study suggest that both the B and C in CBT for voices can contribute to positive outcomes within routine clinical practice.