Excessive fear and avoidance in relatively safe situations can lead to a narrowing of one's behavioral repertoire and less engagement with valued aspects of living. Ultimately, these processes can reach clinical levels, as seen in anxiety, trauma, and obsessive-compulsive disorders. Research on the basic behavioral processes underlying successful treatment with exposure therapy is growing, yet little is known about the mechanisms contributing to clinical relapse. Until recently, these mechanisms have largely been conceptualized in terms of Pavlovian return of fear, with relatively little research into operant processes. In the current paper, we briefly review translational research in anxiety disorders and the connections between fear and avoidance, focusing on recent work in the acquisition, extinction, and relapse of avoidance behavior and the generalization of this learning through arbitrary symbolic relations. We then introduce one possible treatment approach to mitigating clinical relapse, acceptance and commitment therapy (ACT), and provide a conceptual analysis for why ACT may be especially well-situated to address this issue. Finally, we end with potential directions for future research on treatment and relapse of anxiety disorders.