OBJECTIVE:Effective treatments for social anxiety disorder (SAD) exist, but additional treatment options are needed for nonresponders as well as those who are either unable or unwilling to engage in traditional treatments. Mindfulness-based stress reduction (MBSR) is one nontraditional treatment that has demonstrated efficacy in treating other mood and anxiety disorders, and preliminary data suggest its efficacy in SAD as well. METHOD: Fifty-six adults (52% female; 41% Caucasian; age mean [M] ± standard deviation [SD]: 32.8 ± 8.4) with SAD were randomized to MBSR or an active comparison condition, aerobic exercise (AE). At baseline and post-intervention, participants completed measures of clinical symptoms (Liebowitz Social Anxiety Scale, Social Interaction Anxiety Scale, Beck Depression Inventory-II, and Perceived Stress Scale) and subjective well-being (Rosenberg Self-Esteem Scale, Satisfaction with Life Scale, Self-Compassion Scale, and UCLA-8 Loneliness Scale). At 3 months post-intervention, a subset of these measures was readministered. For clinical significance analyses, 48 healthy adults (52.1% female; 56.3% Caucasian; age [M ± SD]: 33.9 ± 9.8) were recruited. MBSR and AE participants were also compared with a separate untreated group of 29 adults (44.8% female; 48.3% Caucasian; age [M ± SD]: 32.3 ± 9.4) with generalized SAD who completed assessments over a comparable time period with no intervening treatment. RESULTS: A 2 (Group) x 2 (Time) repeated measures analyses of variance (ANOVAs) on measures of clinical symptoms and well-being were conducted to examine pre-intervention to post-intervention and pre-intervention to 3-month follow-up. Both MBSR and AE were associated with reductions in social anxiety and depression and increases in subjective well-being, both immediately post-intervention and at 3 months post-intervention. When participants in the randomized controlled trial were compared with the untreated SAD group, participants in both interventions exhibited improvements on measures of clinical symptoms and well-being. CONCLUSION: Nontraditional interventions such as MBSR and AE merit further exploration as alternative or complementary treatments for SAD.