The purpose of the study was to determine the validity and reliability of a revised observation and evaluation instrument of middle and secondary pre-service clinical teaching to be used as part of the clinical supervision cycle and for formative purposes. The North Texas Appraisal of Classroom Teaching (NTACT) serves as a performance assessment tool utilized by a south-central university-based educator preparation program for the evaluation and supervision of pre-service teachers during their last semester of their program. The researcher piloted and field-tested a redesigned observation and evaluation instrument (NTACT-V2) on observer participants with varying educational experiences in the south-central region. To accumulate evidence of validity and reliability, this study employed methods of factor analysis and generalizability study for developing a valid and reliable instrument to guide the refinement process of the NTACT observation and evaluation instrument. Some of the significant conclusions reached in this study were (a) the NTACT-V2 is a practical, user-friendly classroom observation and evaluation instrument; (b) the instrument refined and developed in this study exhibits appropriate content, face, and criterion validity as determined by a panel of experts and an extensive review of the literature; and, (c) a variety of observers can use the evaluation instrument with …