It is a widely accepted thesis in the cognitive sciences and in naturalistic philosophy of mind that the contents of at least some mental representations are innate. A question that has popped up in discussions concerning innate mental representations is this. Are externalist theories of mental content applicable to the content of innate representations? Views on the matter vary and sometimes conflict. To date, there has been no comprehensive assessment of the relationship between content externalism and content innateness. The aim (...) of this paper is to provide such an assessment. I focus on the notions of innateness that are employed in innateness hypotheses within the cognitive sciences and adjacent fields of philosophy, and on causal externalist theories of content. I distinguish between three accounts of what being innate might amount to in innateness hypotheses within the cognitive sciences, and between three types of causal externalism. I explain what the possibility of innate externalistically individuated representations depends upon given all nine combinations. I explain why causal externalism can be true of innate mental representations, given but one of these combinations. (shrink)