The purpose of this paper is to introduce the Teacher Performance Rate and Accuracy Scale (TPRA) which is a method of direct teacher observation used in the teacher evaluation and training component of the Comprehensive Application of Behavior Analysis to Schooling (CABAS [R]) model of schooling. The TPRA builds on the concept of academic engaged time (a measure frequently employed during ecobehavioral assessment) by counting the presence or absence of learn units (interlocking three-term contingencies for both students and teachers) during instruction. Implementation procedures for the TPRA, its application for identification and analysis of instructional problems, and its use for training and ongoing evaluation of teachers are presented and discussed. (Contains 4 tables and 1 figure.)