Smokers in stages of low readiness to quit (immotives and precontemplators) and smokers in stages of high readiness to quit (contemplators and preparers) were randomly allocated to 1 of 4 tailored intervention conditions offering outcome information, self-efficacy-enhancing information, both sorts of information, or no information. Data on 1,540 smokers, stratified by stage, were analyzed. The primary outcome measure was stage transition. The hypotheses with regard to stage-matched information for immotives and precontemplators were not verified. With regard to contemplators and preparers, the following was found: Compared with the control group, contemplators benefited the most from both sorts of information, whereas preparers benefited the most from self-efficacy-enhancing information only. Comparisons between contemplators and preparers who were assigned to the matched treatment and contemplators and preparers who were assigned to the mismatched treatment supported these findings.