The Picture Exchange Communication System (PECS) is a picture-based alternative communication method that is widely accepted and utilized with individuals with disabilities. Although prior studies have examined the clinical efficacy of PECS, none have experimentally evaluated its manualized training structure. We experimentally evaluated the effects of training during each of the 6 phases of PECS with 7 children with developmental or language disorders. For all 7 participants, PECS responses consistently increased only after training was completed for each of the first 4 phases, but increases in PECS responses occurred during tests of Phases 5 and 6 as soon as training was completed in Phase 4. Consistent with prior research, PECS was taught in a short period of time and required few prerequisite skills. However, 3 of the 7 participants had difficulty with some aspects of training and were able to acquire the targeted skills only after procedural modifications were made. (Contains 1 table and 7 figures.)