OBJECTIVES: This study evaluated the feasibility and initial efficacy of a 12-week group mindfulness-based intervention tailored for persons with social anxiety disorder (MBI-SAD). The intervention includes elements of the standard mindfulness-based stress reduction program, explicit training in self-compassion aimed at cultivating a more accepting and kinder stance toward oneself, and use of exposure procedures to help participants practice responding mindfully to internal experiences evoked by feared social situations. METHODS: Participants were randomly assigned to the MBI-SAD (n = 21) or a waitlist (WL) (n = 18) control group. Feasibility was assessed by the number of participants who completed at least 75% of the 12 weekly group sessions. Primary efficacy outcomes were clinician- and self-rated measures of social anxiety. Other outcomes included clinician ratings of illness severity and self-rated depression, social adjustment, mindfulness, and self-compassion. RESULTS: The MBI-SAD was acceptable and feasible, with 81% of participants attending at least 75% of sessions. The MBI-SAD fared better than WL in improving social anxiety symptom severity (p ≤ 0.0001), depression (p ≤ 0.05), and social adjustment (p ≤ 0.05). The intervention also enhanced self-compassion (p ≤ 0.05), and facets of mindfulness (observe and aware; p ≤ .05). MBI-SAD treatment gains were maintained at 3-month follow-up. CONCLUSIONS: These preliminary findings suggest that an MBI that integrates explicit training in self-compassion and mindful exposure is a feasible and promising intervention for social anxiety disorder. The next step is to compare the MBI-SAD to the gold standard of cognitive-behavior therapy to determine equivalence or noninferiority and to explore mediators and moderators of treatment outcome.