The present study examines whether children display different frequencies of behaviors at birthday party as compared to non-birthday party settings, and elucidates in which setting behavior is more predictive of later child functioning. Behavior in birthday and non-birthday contexts was examined at 12 and 24 months of age for 56 children with autism spectrum disorder (ASD). The results of this study indicate that context does matter for young children's behavior and leads to a different picture of behavioral functioning. For children with ASD, behaviors from non-birthday videotapes are more predictive of functioning later in childhood. The findings suggest that close attention must be paid to contextual factors that may influence young children's behavior.