Intentionality is an important part of the classic mind-body problem, and naturalists need to give an account of it. This should include an explanation for how mental states can have contents, both propositional and non-propositional. Many types of reductive explanations have been proposed, but none widely accepted. The two most popular are 1) accounts somehow based on causal connections or information-carrying regularities between mental representations and their referents or truth conditions, and 2) functionalist type "conceptual role" or "causal role" accounts based on causal connections among mental states and/or mental representations, possibly extending into the world as well. Two less popular approaches are 3) success semantics (according to which truth conditions are determined by success in some sense) and 4) resemblance theories (whereby representations denote by means of resemblance of some sort, e.g. isomorphism). Teleology, usually in the form of evolutionary function, may be brought in to solve problems that arise for any of the above, particularly in order to solve "disjunction problems" like allowing for the possibility of error and misrepresentation. The "phenomenal intentionality" strategy is a new kid on the block, and there are non-reductive approaches as well, including non-reductive versions of the foregoing, as well as interpretivism (content is determined by constrained possibilities for interpretation) and deflationism (claims about mental state content are largely trivial and uninformative).