Thirty-three speech-language pathologists (SLPs) were interviewed and observed by two teams of evaluators using a generic teacher performance assessment instrument. Interviews and therapy observations were recorded on videotape and all Ss were rated on their overall demonstration of competence by a panel of practitioners and teacher educators. As an external criterion measure the rankings of the panel and the classifications of the SLPs were compared to the ratings from two performance assessment instruments. Those items that were positively and significantly related to the external criterion were considered valid and formed the revised instrument. The Special Education Competencies for Teaching was found to have content, construct, and concurrent validity. (Author/CL)