Children typically acquire linguistic and conceptual knowledge simultaneously, allowing reciprocal beneficial effects. However, there is still considerable debate about the nature of both knowledge systems and the extent to which the two knowledge systems interact. A growing body of evidence supports the view that conceptual knowledge and language acquisition and use are grounded in situated action, which has led to the formulation of various theories of embodied cognition and language. Yet there is also considerable evidence that language also exerts important effects on conceptual knowledge. This paper reviews such theories and evidence in relation to research into infants’ early conceptual knowledge. Despite the importance of categories and categorical relations for conceptual knowledge, research suggests that early conceptual knowledge may be organized based on situational or thematic relations. Categorical relations may depend on language acquisition because they are abstract relations, and this may be a key aspect in which linguistic knowledge influences conceptual knowledge during development and across the lifespan.