This case study presents the 21-session cognitive-behavioral treatment of a young adult female diagnosed with Generalized Social Phobia (GSP) and Avoidant Personality Disorder (APD). Therapy utilized Beck’s modified cognitive therapy of personality disorders in addition to behavioral skills training. Therapist observation, client self-report, and objective measurements were used to assess behavioral change. Post intervention administrations of the Beck Depression Inventory–II (BDI-II), Beck Anxiety Inventory (BAI), and Minnesota Multiphasic Inventory–2 (MMPI-2) evinced a clinically significant reduction of symptoms. The results indicate that a short-term cognitive-behavioral approach may prove efficacious when treating APD.