Two studies of 100 children aged 3-12 years examined theory of mind (ToM) understanding via explanations and predictions in hearing preschoolers and ToM-delayed deaf children. Study 1's 75 children (31 deaf; 44 hearing) displayed an "explanation advantage," devising valid epistemic ToM explanations despite failing simpler forced-choice false-belief (FB) prediction tests. This novel discovery for deaf children extended to unexpectedly frequent cognitive ("think" or "know") explanations. Study 2 (with 25 additional deaf children; M[subscript age] = 9) showed that microgenetic FB explanation practice resulted in significant gains on FB prediction posttests that were absent in a non-ToM control group. Implications for (a) explanation's interconnection with conceptual development, (b) designing ToM interventions, and (c) teaching deaf and hearing children are discussed.