In this experiment, syntactic constraints on the retrieval of orthography were investigated using homophones embedded in sentence contexts. Participants typed auditorily presented sentences that included a contextually appropriate homophone that either shared part of speech with its homophone competitor (i.e., was syntactically unambiguous) or had a different part of speech (was syntactically ambiguous). Each homophone was preceded by an unrelated word or a prime; primes were orthographically related to the competitor and shared or differed from the competitor's part of speech. For syntactically unambiguous homophones, more errors occurred overall, and priming increased errors independent of the prime's part of speech. For syntactically ambiguous homophones, priming occurred only following primes that shared part of speech with the competitor. These results demonstrate that written homophone errors can occur during lemma retrieval or during orthographic encoding, with the particular stage depending on the syntactic ambiguity of the homophone to be produced. (Contains 4 footnotes, 3 tables and 2 figures.)