Semantic externalism in contemporary philosophy of language typically – and often tacitly – combines two supervenience claims about idiolectical meaning (i.e., meaning in the language system of an individual speaker). The first claim is that the meaning of a word in a speaker’s idiolect may vary without any variation in her intrinsic, physical properties. The second is that the meaning of a word in a speaker’s idiolect may vary without any variation in her understanding of its use. I here show that a conception of idiolectical meaning is possible that accepts the “anti-internalism” of the first claim while rejecting (what I shall refer to as) the “anti-individualism” of the second. According to this conception, externally constituted idiolectical meaning supervenes on idiolectical understanding.