How do people glean meaning from language? A Principle of Compositionality is generally understood to entail that the meaning of every expression in a language must be a function of the meaning of its immediate constituents and the syntactic rule used to combine them. This paper explores perspectives that range from acceptance of the principle as a truism, to rejection of the principle as false. Controversy has arisen basedon the role of extra-constituent linguistic meaning (idioms; certain cases of paradigmatic morphology; constructional meanings; intonation), and context (e.g., metonymy; the resolution of ambiguity and vagueness).