Subjects were shown pairs of letter strings and had to decide as quickly as possible whether both strings were words. The word pairs included associates (e.g., cat-dog), words not normatively associated that had been rated by other subjects as semantically similar (e.g., nurse-wife), and unrelated control pairs (e.g., bread-stem). Both associates and semantically related pairs were responded to more quickly than were the corresponding control pairs. The magnitude of the facilitation for the associates appeared to be related more to the semantic similarity ratings than to measures of either direct or indirect associative strength. It was concluded that the encoding of a word can be facilitated by the prior processing of a semantically related word.