Dialectical Behavior Therapy (DBT) and Acceptance and Commitment Therapy (ACT) are often grouped together as “third-wave” cognitive behavioral therapies and have become increasingly popular among therapists treating a wide variety of presenting problems. This paper describes areas of conceptual overlap between DBT and ACT, notably both being principle-based approaches to addressing psychological suffering and use of contextual-behaviorism and acceptance. We discuss areas of divergence in terms of models for the development and maintenance of psychological suffering, specifically DBT and ACT being rooted in the biosocial model and relational frame theory, respectively. These models have downstream effects on theorized mechanisms of change (e.g., emotion regulation, psychological flexibility), treatment structure and delivery. Differences are often nuanced (e.g., degree of emphasis on mindfulness practice and values identification, directive versus non-directive approach), relying on ongoing case conceptualizations and consideration of contextual factors. We touch on the empirical evidence for DBT and ACT. Finally, we describe considerations for future research, including research aimed at mediation and moderation studies and comparing modifiable processes of change, to better determine whom would most benefit from these treatments to advance clinical care.