The processes and mechanisms of theory-of-mind development were examined via a training study of false-belief conceptions in deaf children of hearing parents (N = 43). In comparison to 2 different control conditions, training based on thought-bubble instruction about beliefs was linked with improved false-belief understanding as well as progress on a broader theory-of-mind scale. By combining intervention, microgenetic, and developmental scaling methods, the findings provide informative data about the nature and mechanisms of theory-of-mind change in deaf children, as well as an initial demonstration of a useful intervention for enhancing social cognition in deaf children of hearing parents. The methods and results also point to possible avenues for the study of conceptual change more generally.