This chapter characterizes the concept of cognitive opacity, outlines the nature of the learnability problem it represents for mechanisms of cultural learning, and speculates about its evolutionary origins. It argues that during hominid evolution, a new type of social learning system has been selected that is specialized to ensure efficient intergenerational transfer of cognitively opaque cultural contents from knowledgeable to naïve conspecifics. The design structure of this cue-driven cognitive adaptation of mutual design, called natural pedagogy, is then described. Pedagogy theory is contrasted with currently dominant alternative approaches to cultural learning that are based on simulation and identification processes by comparing how these respective models can account for recent evidence on early relevance-guided selective imitative learning, on the one hand, and on young infants' interpretation of others' referential emotion expressions in ostensive versus incidental observation contexts, on the other hand. It is argued that many early emerging social cognitive competences involving ostensive communicative interactions (such as imitative learning, social referencing, or protodeclarative pointing) are better accounted for in terms of the primarily epistemic functional perspective of natural pedagogy than in terms of human-specific primary social motives to identify with and imitate other humans, and share one's mental states with others, as hypothesized by the alternative simulation-based approaches. Finally, the implications of pedagogy theory for reconceptualizing the nature of the early development of understanding others as having separate minds with different knowledge contents are briefly explored.