Objective: Children with ADHD experience peer problems that may place them at risk for adverse outcomes. Using a short-term longitudinal design, this study links specific behaviors to peer functioning in groups of previously unfamiliar children with ADHD. Method: The participants were 268 children with ADHD who took part in an intensive summer treatment program. The program used a comprehensive behavioral point system that yielded observational data for 12 behavioral categories. These behavioral categories were used to predict peer acceptance, rejection, and liking assessed at three times during the program. Results: Following activity rules, helping, whining, and attention emerged as best predictors of initial peer status. Subsequent helping behaviors and activity rule following predicted changes in peer status, but their contributions were small. Conclusion: The results indicate that increasing helping and rule-following behaviors may improve peer functioning of children with ADHD in similar settings. (Contains 5 tables.)