The purpose of this study was to estimate the validity of the Competence subscale of the Teacher Staff Development Survey (TSDS) as a measure of the teacher efficiency construct. Results from regular education elementary school teachers (N=296) revealed a subscale structure of the TSDS that differed from the subscale structure originally designed by the Tempe (Arizona) School District. Specifically, six independent factors (i.e., subscales) were revealed: (1) Teacher Efficacy; (2) Organizational Efficacy; (3) Inclusion; (4) Resources; (5) Teaming; and (6) Self-Evaluation. The Competence subscale of the TSDS, as originally proposed by the Tempe School District, did not emerge as an independent subscale. Instead, this scale appeared to break down into two separate subscales: Teacher Efficacy and Organizational Efficacy. The Teacher Efficacy subscale of the TSDS was found not only to be a valid measure of teacher efficacy, but also to provide a better means of assessing the construct than the Competence subscale originally proposed by the Tempe School District. This subscale may be conceptualized as a measure of the personal teaching efficacy dimension of teacher efficacy. As an index of personal teaching efficacy, the Teacher Efficacy subscale appears to have utility in assessing the effectiveness of not only Project RIDE (Responding to Individual Differences in Education), but also other programs in which the objective is to enhance teachers' skills in dealing with "at-risk" students. The Teacher Efficacy subscale may not be appropriate, however, for evaluating programs where influencing teachers' perceptions of the general teaching efficacy dimension is of greater concern. Contains 4 tables and 24 references. (TS)