Participation is limited to veterans who satisfy a validated case definition of GWI and whose utilization is at (or above) the 80th percentile. A long-term goal of the proposed research is to make specialized Telephone CBT services widely available to veterans regardless of their geographic location. A previously validated CBT program for GWI has been adapted in consultation with Dr. Charles Engel. The proposed study represents the first randomized (multicenter) trial of Telephone CBT designed to ameliorate GWI and reduce unnecessary reliance on VA health care services. A total of 150 eligible veterans will be assigned to one of three groups: (I) Telephone CBT + Customary Medical Care; (II) In-Person CBT + Customary Medical Care; or (III) Customary Medical Care only.