We test the claim that learning and using language for spatial relations can influence spatial representation and reasoning. Preschool children were given a mapping task in which they were asked to find a "winner" placed in a three-tiered box after seeing one placed in a virtually identical box. The correct choice was determined by finding the corresponding relative location in the test box, making it a difficult task for preschool children. We found that hearing language for spatial relations facilitated children's mapping performance. We found effects at younger ages on easier tasks (Experiments 1 and 2) and at older ages on harder tasks (Experiment 3). The effects of spatial relational language differed predictably according to the semantics of the terms children heard (Experiment 4). Finally, the effects of spatial language were maintained over time (Experiment 5): children given one initial exposure to the spatial terms maintained their advantage over baseline children when they again carried out the mapping task 2 days later, with no further exposure to the spatial terms. The evidence is consistent with the explanation that language bolsters children's spatial encodings, which in turn supports their mapping performance.