In a repetition priming paradigm, young and older participants read aloud prime words that sometimes shared phonological components with a target word that answered a general knowledge question. In Experiment 1, prior processing of phonologically related words decreased tip-of-the-tongue states (TOTs) and increased correct responses to subsequent questions. In Experiment 2, the priming task occurred only when the participant could not answer the question. Processing phonologically related words increased correct recall, but only when the participant was in a TOT state. Phonological priming effects were age invariant, although older adults produced relatively more TOTs. Results support the transmission deficit model that the weak connections among phonological representations that cause TOTs are strengthened by production of phonologically related words. There was no evidence that phonologically related words block TOT targets.The tip-of-the-tongue state (TOT) is a relatively common type of speech error in which a word retrieval failure is coupled with a strong feeling of knowing and often with a considerable sense of frustration at the inaccessibility of the desired word. Typically, a person can access semantic and syntactic properties of the TOT word and partial phonological properties such as initial sound or number of syllables, although the complete phonology remains inaccessible (e.g., A. S. Brown, 1991;R. Brown & McNeill, 1966;Koriat & Lieblich, 1974;Miozzo & Caramazza, 1997;Vigliocco, Antonini, & Garrett, 1997). Resolution of a TOT is as compelling as the TOT onset when it occurs spontaneously, with the target word popping into mind at a time when retrieval attempts have been abandoned (Burke, MacKay, Worthley, & Wade, 1991;A. S. Brown, 1991;Reason & Lucas, 1984). In this article, we investigate the phonological encoding processes that are fundamental to speech production and are implicated in the cause of TOTs and their spontaneous resolution. We also investigate the role of phonological encoding processes in aging effects. TOTs are a hallmark of old age, increasing in frequency with normal aging in both experimental and naturalistic studies (A. S. Brown & Nix, 1996; Lori E. James, Department of Psychology, Claremont Graduate University; Deborah M. Burke, Department of Psychology, Pomona College.Lori E. James is now at the Department of Psychology, University of California, Los Angeles.This research was supported by a Haynes Fellowship and Grant R37 AGOS835 from the National Institute on Aging. Portions of this research were reported at the Cognitive Aging Conference, Atlanta, GA, April 1994, and at the meeting of the Psychonomic Society, Los Angeles, CA, November 1995. We thank Jennifer Taylor for phonetic transcriptions and Kathryn Bock, Don MacKay, Alan Brown, Tim Perfect, and an anonymous reviewer for very helpful comments on a draft of this article.Correspondence concerning this article should be sent to Deborah M. Burke, Department of Psychology, Pomona College, 550 Harvard Avenue, Claremont, Ca...