When do children acquire a propositional attitude folk psychology or theory of mind? The orthodox answer to this central question of developmental Theory of Mind research had long been that around age 4 children begin to apply “belief” and other propositional attitude concepts. This orthodoxy has recently come under serious attack, though, from two sides: Scoffers complain that it over-estimates children’s early competence and claim that a proper understanding of propositional attitudes emerges only much later. Boosters criticize the orthodoxy for underestimating early competence and claim that even infants ascribe beliefs. In this presentation, the orthodoxy is defended on empirical grounds against these two kinds of attacks. On the basis of new evidence, not only can the two attacks safely be countered, but the orthodox claim can actually be strengthened, corroborated and refined: what emerges around age 4 is an explicit, unified, flexibly conceptual capacity to ascribe propositional attitudes. This unified conceptual capacity contrasts with the less sophisticated, less unified implicit forms of tracking simpler mental states present in ontogeny long before. This refined version of the orthodoxy may be most plausibly spelled out in some form of 2-systems-account of theory of mind.