The purpose of this study was to evaluate the effectiveness of a psychosocial approach to the treatment of Selective Mutism (SM). Four children with SM along with their parents and teachers participated in the study. A comprehensive assessment was completed; manualized treatment was implemented through a conjoint behavioral consultation approach, and a randomized multiple baseline experimental research design was utilized to evaluate outcomes. The results indicated that modest improvements in mutism behaviors were consistent with the onset of treatment, although these results did not generalize to the school day for all children. Parents rated the treatment as effective and acceptable. A discussion of the results of this study as well as the implications for practice and future research is provided. (Contains 6 tables, 4 figures, and 1 footnote.)