Engagement is a core component of effective educational programs for children with autism. Analysis of 711 naturalistic goal-directed classroom behaviors of four school-age children with autism and four comparable children with Down syndrome (DS) was conducted. The definition of engagement was expanded to include child compliance and congruence. A main finding was both child and environmental factors influenced type of engagement. Children with DS produced 20% more goal-directed behaviors that were both congruent and compliant compared to children with autism. Large group instruction was associated with less congruent engagement but more compliant engagement for children with autism. These findings suggest specific types of engagement which may lead to advances in developing evidence-based practices for specific developmental disorders.