This study investigated how lexical access in naming tasks (picture naming, naming to open-ended sentences, and naming to category exemplars) might be influenced by different lexical factors during adolescence and adulthood. Participants included 1075 individuals, ranging in age from 12 to 83 years. Lexical factors examined included word frequency and familiarity, age of acquisition, neighborhood density, and phonotactic probability. As expected, each of these factors influenced lexical access, and there was a general trend towards less accurate naming with age. More interestingly, word frequency and neighborhood density both showed larger effects for adolescents than for adults, but then showed constant effects on lexical access throughout adulthood. Phonotactic probability showed constant effects across the lifespan. Effects of word familiarity and age of acquisition interacted with age in adulthood; lexical access of older adults was more greatly affected by a word's familiarity and age of acquisition than was the lexical access of younger adults. These lexical factors impact on adult naming so that words that were learned later in life and which are judged to be less familiar are more difficult to retrieve then their counterparts (words learned earlier and judged to be more familiar) as individuals age. This suggests that age of acquisition and familiarity may play a protective role in adult naming. In contrast, word frequency and form-based properties of words appear to have similar effects throughout adulthood. Implications of these findings for theories of aging and for models of lexical access are discussed. (Contains 5 figures and 3 footnotes.)