This study examined the efficacy of an 8-week telephone-administered cognitive-behavioral therapy (CBT) for the treatment of depressive symptomatology in multiple sclerosis (MS) patients. The treatment, Coping with MS (CMS), included a patient workbook designed to structure the treatment, provide visual aids, and help with homework assignments. Thirty-two patients with MS, who scored at least 15 on the Profile of Mood States Depression-Dejection scale, were randomly assigned to either the telephone CMS or to a usual-care control (UCC) condition. Depressive symptomatology decreased significantly in the CMS condition compared with the UCC condition. Furthermore, adherence to interferon beta-1a, a disease-modifying medication for the treatment of MS, was significantly better at the 4-month follow-up among patients who received CMS as compared with those in the UCC condition.