We describe a training program to teach applied behavior analysis (ABA) knowledge competencies to paraprofessional staff (N = 47) at a habilitation services agency for adults with developmental disabilities. Before and following training, staff completed assessment of knowledge tests for three content areas: basic learning principles, instructional strategies, and prompting and prompt-fading methods. Training was implemented in a group format that included a standardized curriculum, didactic presentation, case illustration, and directed discussion. Average tests scores (percent correct) for the three ABA knowledge competencies increased from pretraining to posttraining. Practical considerations relative to large-scale staff training are discussed. (Contains 1 table and 1 figure.)