RecruitingBehavioural interventionEffectiveness- Implementation Trial of the Function-Based Elopement TreatmentThe goal of this clinical trial is to test whether the Function-Based Elopement Treatment (FBET) can reduce elopement in children aged 4-12 with autism spectrum disorder (ASD), and to assess its feasibility in community-based Applied Behavior Analysis (ABA) clinics. Researchers will evaluate FBET in a single-arm open-label trial in one clinic, followed by a comparison of FBET to treatment as usual (TAU) across at least six ABA clinics to evaluate effectiveness and implementation. The main questions it aims to answer are: * Is it feasible to use FBET in community-based ABA clinics? * Does FBET reduce elopement? * Does FBET lead to greater clinical improvement? Participants will: * Receive 12 sessions of FBET over 20 weeks with trained BCBAs or receive treatment as usual * Complete caregiver assessments at baseline and endpoint * Engage in caregiver training and practice treatment between appointments