Doing crossword puzzles is a popular pastime; no one knows how many people do them, but estimates go as high as 50 million or more in the United States alone. Success at crossword puzzles taxes several aspects of memory and cognition. The purpose of this article is to consider hints that crosswords provide and questions that they prompt regarding how the mind works. Implicated topics include word associations, lexical memory search, semantic priming, the sparseness of word space, list generation, the feeling of knowing and of not knowing, mental aging, and the crossword puzzle as a vehicle for studying cognition.