The present study examined the effects of therapist presence and the addition of relaxation training on the efficacy and generalizability of in vivo exposure procedures in the treatment of multiply-phobic individuals. Thirty-two individuals who were severely phobic of at least two objects/situations were assigned to one of three treatment groups or a waiting list control group, but received treatment for only one phobia. The Exposure Alone group received prolonged exposure to a phobic stimulus while alone in a room with that stimulus. The Exposure + Relaxation group were also exposed to a phobic stimulus but had received additional training in a relaxation technique. Subjects in the Exposure + Therapist group were accompanied by a nonanxious/nonavoiding “therapist” during exposure sessions. All treatment groups improved significantly, but the Exposure + Therapist group demonstrated significantly greater extinction of fear responses related to the treated phobias than the other groups. The Exposure + Relaxation group demonstrated the greatest generalization of treatment effects to untreated phobias. Clinical and theoretical implications are discussed.