Background: Studies testing Web-based computer-tailored education in real-life settings are now needed. Purpose: The aim of this study is to examine the effectiveness and applicability of an interactive computer-tailored fat reduction intervention, which was previously tested as efficacious in a controlled setting, delivered to a broader population by local health promotion services. The impact of the computer-tailored intervention is compared with a generic intervention and with a no-intervention control group. Methods: A quasi-experimental design was used assigning 6 companies randomly to (a) the computer-tailored intervention condition, (b) the generic intervention condition, and (c) the no-intervention control condition. Participants (N = 337) completed validated baseline and posttest questionnaires and received the personal feedback immediately through the company’s intranet. A structured interview with the project coordinators assessed the process that the companies had passed through to disseminate the fat intake intervention. Results: Six months postbaseline, the results showed that the computer-tailored intervention to reduce fat intake implemented through worksites was more effective in decreasing employees’fat intake compared with a generic intervention, F = 23.5, p < .001, or no intervention, F = 28.1, p < .001. Moreover, the dissemination strategy used is feasible for local health promotion services. Conclusions: This study can be regarded as an effective “real-life” trial with an implementation strategy that can be used for large scale dissemination.