Adults completed a lexical decision task in which they saw two strings of letters on each trial and were asked to respond "yes" only if both strings were words. Later, participants were tested for incidental free recall and incidental forced-choice recognition of the words presented in the lexical decision task. These tasks were given to 20 young (mean age = 31.1 years) and 20 old (mean age = 69.5 years) non-student adults in Experiment 1, and to 20 young college students in Experiment 2. In both experiments, semantic priming occurred, i.e., lexical decisions were faster when the words within a pair were related than when they were not. For the college students in Experiment 2, but not for the non-students in Experiment 1, this effect was greater for high-dominance pairs (e.g., BIRD-ROBIN) than for low (e.g., BIRD-DUCK). Experiment 1 revealed no age differences in priming, but significant age differences favoring the young in both free recall and recognition. The results are interpreted in light of theories that distinquish between automatic and effortful activation of semantic memory.