In domains with multiple competing goals, people face a basic challenge: How to make their strategy use flexible enough to deal with shifting circumstances without losing track of their overall objectives. This article examines how young children meet this challenge in one such domain, tic-tac-toe. Experiment 1 provides an overviews of development in the area; it indicates that children's tic-tac-toe strategies are rule based and that new rules are added one at a time. Experiment 2 demonstrates that even young children flexibly tailor their strategy use to meet shifting circumstances