Participation in aphasia therapy generally results in positive outcomes. Constraint-induced aphasia therapy (CIAT) researchers in particular make bold claims about the efficacy of the approach, but pervasive methodological problems throughout the literature detract from the impact of those claims. The study reported in this dissertation was designed to determine the effect of CIAT on standardized measures of language ability, functional communication, and quality of life. In addition, continuous assessment of dependent variables occurred to ensure that improvements in naming and discourse behaviors could be attributed to CIAT and not to other extraneous factors. Six adults with aphasia participated in this modified single-subject, multiple-baseline across individuals design consisting of a baseline, treatment, and maintenance phase. Results provide the new information that the CIAT protocol utilized in this study resulted in a reduction in activity and participation limitations. Furthermore, this study demonstrated the effect of CIAT on naming of trained items and on untrained discourse tasks though the stability criteria used in this study did not prevent the occurrence of accelerating trends in baseline data and therefore reduces the impact of these claims. Results also supply needed information about treatment elements and preliminary information about dosage that will serve as a platform for future research. Suggestions for future research geared towards refining aphasia treatment are provided.