BACKGROUND: Cognitive-behavioral therapies often are recommended for anxiety disorders. However, treatment adherence and compliance are major barriers for these treatments, which are often delivered in 10 to 12 sessions over several months. This randomized controlled trial (trial registration NCT02915874 at www.clinicaltrials.gov) examined the effectiveness and feasibility of a 1-day cognitive-behavioral intervention for mixed anxiety.

METHODS: A total of 72 adults with moderate-to-high anxiety were randomized into a 1-day acceptance and commitment therapy (ACT) workshop (n = 44) or treatment as usual (n = 28). Follow-up assessments were conducted 6 and 12 weeks after the workshop. Clinical outcomes were anxiety (primary) and depressive (secondary) symptoms, as measured by the Beck Anxiety Inventory and Beck Depression Inventory-II, respectively. Proposed mediators of ACT—psychological flexibility and committed action—also were examined.

RESULTS: Participants assigned to the ACT workshop showed significant improvements in anxiety (beta = −1.13; P = .02) and depression (beta = −1.09; P = .02) after 12 weeks. Consistent with the theoretical model, these clinical improvements were mediated by psychological flexibility and committed action. Notable limitations included the sample size, inability to blind to treatment condition, and a racially and ethnically homogeneous sample.

CONCLUSIONS: Our 1-day ACT workshop was effective for anxiety with cooccurring depressive symptoms. One-day interventions are a promising alternative to weekly treatments.