Depression and anxiety are the most common mental health disorders seen in clinical practice and they are highly comorbid. Cognitive behavioral therapy (CBT) has been demonstrated as an effective treatment for both depression and anxiety but is often not available to all individuals who could benefit from it. This paper investigates the effectiveness of a mixed-diagnosis group CBT intervention that incorporates mindfulness meditation for individuals presenting with depression and/or anxiety: CBT Basics II. This intervention was evaluated across two distinct mental health programs to determine both if it can demonstrate positive results and if it is feasible to implement in these types of programs. Sample 1 (n = 42 completers) consisted of higher-functioning individuals in a general mental health program. Sample 2 (n = 53 completers) consisted of individuals with more chronic and severe mental health diagnoses. Overall, intent-to-treat analyses revealed improvements in psychiatric symptoms, and increases in CBT knowledge and mindfulness skill across both programs. This indicates that CBT Basics II is effective across diverse mental health populations and shows promise for improving access to CBT. (Contains 4 tables and 2 videos.)