This 5-year longitudinal study investigated advanced theory-of-mind (AToM) development in 161 German 5- to 10-year-olds (89 females, 72 males). Core aspects of AToM developed nonlinearly, with children reaching a milestone at the age of 7 years, around when they attained the conceptual insight that mental states can be recursive. In late elementary school, a multicomponent battery was used. Performance on many aspects of AToM was predicted by information-processing skills (intelligence and language at 6 years), but not by the age when children acquired the basic conceptual insight; only some naturalistic, social-interpretative tasks were correlated with children's age at acquisition. This study documents significant developmental progressions in middle-childhood AToM and suggests that different mechanisms may underlie diverse aspects of social cognition.