This investigation is an attempt to apply the principles of the experimental analysis of behavior to the stuttering behavior of two clinical subjects. The experimental manipulations were performed in order to bring about a decrement in the stuttering rate of the two subjects.

The use of so many different therapeutic approaches to stuttering raises frequent questions about methodology and treatment. Confidence in a methodology and treatment approach depends upon follow-up research conducted with systemic analysis of the individuals prior to treatment and following treatment. The purpose of this study was to conduct a follow-up evaluation on R.L. Casteel's Four Stage Stuttering Program at Portland State University and to examine the degree of maintained fluency in relation to entering baseline, time in program, and exit stage.