A three week intensive treatment program for adult stutterers is described. This treatment has evolved from an original program developed by Ingham and Andrews (1973) using speech prolongation techniques, gradual shaping of speech rate to normal, and systematic transfer of skills acquired in the clinic to real life situations. Immediately after intensive treatment, stuttering was virtually eliminated and speech rate and attitudes toward communication were normalized. There was no substantial deterioration in these treatment effects when clients were evaluated in the clinic after two months in the Maintenance Phase of treatment. Speech and attitude measures collected outside the clinic 12--18 months after intensive treatment showed lasting overall improvement in most clients, although some deterioration in fluency from immediate post-intensive treatment levels had occurred in 40% of clients. Covertly collected data supported this finding. Possible causes of relapse and likely solutions are discussed.