We examined 240 children's (3.5-, 4.5-, and 5.5-year-olds) latency to respond to questions on a battery of false-belief tasks. Response latencies exhibited a significant cross-over interaction as a function of age and response type (correct vs. incorrect). 3.5-year-olds' "in"correct latencies were faster than their correct latencies, whereas the opposite pattern emerged for 4.5- and 5.5-year-olds. Although these results are most consistent with conceptual change theories of false-belief reasoning, no extant theory fully accounts for our data pattern. We argue that response latency data provide new information about underlying cognitive processes in theory of mind reasoning, and can shed light on concept acquisition more broadly. (Contains 2 figures.)