ABSTRACT: Unstuck and On Target (UOT) is an executive function (EF) intervention for children with autism spectrum disorders (ASD) targeting insistence on sameness, flexibility, goal-setting, and planning through a cognitive-behavioral program of self-regulatory scripts, guided/faded practice, and visual/verbal cueing. UOT is contextually-based because it is implemented in school and at home, the contexts in which a child uses EF skills.To evaluate the effectiveness of UOT compared with a social skills intervention (SS), 3rd-5th graders with ASD (mean IQ = 108; UOT n = 47; SS n = 20) received interventions delivered by school staff in small group sessions. Students were matched for gender, age, race, IQ, ASD symptomotolgy, medication status, and parents' education. Interventions were matched for 'dose' of intervention and training. Measures of pre-post change included classroom observations, parent/teacher report, and direct child measures of problem-solving, EF, and social skills. Schools were randomized and evaluators, but not parents or teachers, were blinded to intervention type.Interventions were administered with high fidelity. Children in both groups improved with intervention, but mean change scores from pre- to postintervention indicated significantly greater improvements for UOT than SS groups in: problem-solving, flexibility, and planning/organizing. Also, classroom observations revealed that participants in UOT made greater improvements than SS participants in their ability to follow rules, make transitions, and be flexible. Children in both groups made equivalent improvements in social skills.These data support the effectiveness of the first contextually-based EF intervention for children with ASD. UOT improved classroom behavior, flexibility, and problem-solving in children with ASD. Individuals with variable background/training in ASD successfully implemented UOT in mainstream educational settings.