We assessed the reliability and validity of the discrete-trials teaching evaluation form (DTTEF), a 21-item checklist for assessing instructors conducting discrete-trials teaching (DTT). In Phase 1, six consultants in an applied behavior analysis program for children with autism rated the 21 components of the DTTEF with a mean of 6.2 on a 7-point scale, demonstrating high face validity. In Phase 2, two trained observers obtained high interobserver reliability using the DTTEF for live scoring of DTT sessions conducted by tutors and parents teaching a confederate who roleplayed a child with autism. In Phase 3, the DTTEF scores of the DTT performances of the tutors and parents before and after receiving training on DTT were significantly different. In Phase 4, the parents from the previous two phases gave high ratings to the DTTEF on a social validity questionnaire. In the last phase, the DTTEF evaluations of the DTT performances of parents from Phases 2 and 3 compared favorably to ratings of video clips of those performances by the expert consultants from Phase 1, demonstrating high concurrent validity.