We examined developmental changes in the influence of social goals on cooperative and competitive behavior in children between the ages of 6 and 13. Children played a game with a neutrally instructed peer under cooperative and individualistic instructions. The tendency to engage in cooperative and combative moves and to use attentional words varied interactively with age, sex, order of instructions, instructions, and trials. Older children adapted their cooperative behavior to fit assigned goals when individualistic trials preceded cooperation trials, but younger children did not. Older children adapted their competitive behavior on two of the five game trials, but younger children did not adapt their competitive behavior on any trials. We observed no developmental differences in the overall levels of cooperation and competition. However, younger children were more likely to use attentional words than older children, and both age groups used more attentional words under individualistic instructions than under cooperative instructions. The results suggest that older children were more flexible in adapting their social strategies to assigned goals. Flavell (1981), Markman (1981), Schmidt and Paris (1984), and others have proposed that, as they develop, children become more adept at coordinating behavioral strategies with social and cognitive goals. This improvement in coordination of strategies with goals can be caused by increases in the number of strategies available, more effective selection and use of available strategies, or both. Numerous demonstrations that older children are more likely to select goal-or task-appropriate strategies than younger children exist in both the cognitive and social literatures (e.g., Cosgrove & Patterson, 1977;Pressley, Forrest-Pressley, Elliot-Faust, & Miller, 1985). In these demonstrations, older children may benefit from cues associated with the physical context, the social context, task structure, or task stimuli in selecting and deploying effective strategies.Goal adaptation, however, involves more than simply selecting an appropriate strategy in order to pursue an assigned goal. Socially adept individuals would also be able to change their behavior to fit a new goal after successfully pursuing an opposing goal. The most difficult goal adaptation would involve changing behavioral strategies when all task parameters and their associated cues remained constant except the assigned social goal. Demonstrating behavioral change in such a situation would indicate a "flexibility" in strategy use (Schmidt & Paris, 1984) not evident if a child simply selects and deploys a goal-The study reported here was part of a larger project concerning experimental, sociometric, and self-report predictors of peer interaction. Other aspects of the project are reported in T. H. Ollendick & C. R. Schmidt (1987).We wish to thank Nancy Long, Tolly Will, Laurey Simkin, Jim Chadwick, Laurie Meyers, Sue Tomalis, and Greg Scanlon for their help in collecting and coding the data.