Two four-year-old children, Chaislyn and Chris, have an established style of playing together. Their routine is easy to identify: Chris does something to move the play in a particular direction, and Chaislyn follows Chris’s lead, imitating the actions and sounds that Chris makes. Chaislyn likes to create obstacles to assert her presence in the game. These additions receive stern admonishments from Chris, causing them both to laugh. Their laughter signals the end of a round of play; the next round begins with Chaislyn following Chris’ direction again. Chris and Chaislyn take turns deciding when to “stop” a specific action, although they fully intend to start it once again. Their “stop” command functions more as a signal that “we are playing together” than a stop in play motivated by some undesired or completed action.