Why do speakers produce gestures? This study tests the hypothesis that gesture facilitates the conceptual planning of speaking, and in particular, gesture promotes thinking about perceptually present information. This view implies that, when gesture is prohibited, people should be less likely to speak about such information. This prediction was tested among children (N = 50) who solved and explained Piagetian conservation tasks. For one set of conservation tasks, all children were allowed to gesture. For a second set of tasks, some children were prohibited from gesturing by wearing a cloth muff. When children were prohibited from gesturing, they expressed more non-present information and less perceptually present information in their explanations than when allowed to gesture. Thus, gesture production appears to highlight or lend salience to perceptually present information. It is argued that gesture helps speakers decide what to attend to and therefore what to say.