Abstract
Individuals with intellectual and developmental disabilities who engage in severe challenging behavior may comprise 5%–10% of the clinical population. Unfortunately, challenging behavior literature tends to underrepresent adult participants and emphasize efficacy (Does the intervention work?) more often than effectiveness (Does the intervention work in real world settings?). We conducted a systematic program evaluation to examine the effectiveness of a comprehensive behavioral treatment package using a hybrid quasi-experimental consecutive case series design featuring eight adults who experienced the treatment package. The results depicted a substantial decrease in challenging behavior and increase in adaptive behavior across sessions for most participants. Impressive treatment integrity outcomes (M = 84%, range, 82%–90%) showcased that the intervention was implemented as intended. Social validity surveys administered to participants, caregivers, and case managers provide support for the acceptability of the treatment package. Project limitations, clinical considerations, and future directions are discussed.