We have completed 4 years of a 5-year NIH-funded project that is evaluating long-term maintenance associated with functional communication training. Approximately 20 children have enrolled in the project. All children are 6 years of age or younger, have developmental disabilities, and display aberrant behavior such as self-injury. Parents conducted functional analysis and functional communication training session in their homes with weekly coaching from project investigators. Treatment sessions were videotaped and coded using a 6-sec partial-interval recording system. IOA was recorded for approximately 30% of all sessions. Treatment continued for up to 1 year for each participant. Throughout treatment, probes of aberrant behavior, manding, and task completion were conducted in which various components of the treatment package were removed (e.g., mand card) or changed (e.g., time in demands increased from 5 to 15 minutes). The purpose of these probes was to determine if aberrant behavior increased or adaptive behavior decreased when these components were altered. In this talk, I will present the results of these probes and will discuss the results relative to resurgence, maintenance, and response strength.