AWOL behavior of adolescents residing in residential treatment is an issue requiring examination, especially in light of the variety of dangers these adolescents may be exposed to while away from treatment. This study assessed AWOL behavior of three consecutive entry cohorts (n = 234) of adolescents at a large long-term RTC in New York State. AWOL was defined as both (a) running away from the campus and (b) not returning from a home visit. In both cases youth were away from the program without permission. Results indicated that the majority of residents went AWOL at least one time and were equally likely to do so any time within the first 2 years of treatment. Having a history of substance abuse was associated with an increased risk of going AWOL. Areas for future research include replication of the study to help generalize findings and assessment of the effectiveness of interventions to prevent AWOL behavior. (Contains 4 tables.)