Theorists have speculated about the symbolic underpinnings of theory of mind (ToM), but no study has examined them across the main developmental span of ToM. Here, the onset of symbolic understandings in three domains (pretend play, language, and understanding representations) and ToM was examined. Fifty-eight children were tested on batteries of tasks four times from ages 2.5 to 5 years. Some significant interrelations among variables were seen at each age level. Canonical correlation analysis found that a subset of the symbolic variables was significantly related to ToM at ages 4 and 5, providing the best evidence to date that ToM is undergirded by a symbolic element that also supports language, pretend play, and representational understanding.