The acquisition of a theory of mind (ToM) by young children is a much debated topic in developmental psychology. Several incompatible theories concern its possible innate basis and the modes and circumstances of its appearance which allow the child to interpret behavior with new and powerful categories. This paper, extending previous research showing that the acquisition of a ToM is not correlated with chronological age (mental age held constant) but only with mental age, uses a LISREL model to evidence that there is no specific group factor between tasks related to ToM, whose covariance is totally explained by a general intelligence factor. Six tasks were administered to 102 children aged from 3 to 6 years. These findings suggest that, if ToM has an innate basis, the latter is on line before three years of age and that the acquisition of an explicit ToM follows the same rules as any conceptual acquisition.