Although the randomized, controlled trial (RCT) is considered the gold standard in research for determining the efficacy of health education interventions, such trials may be vulnerable to "preference effects"; that is, differential outcomes depending on whether an individual is randomized to his or her preferred treatment. In this study, we review theoretical and empirical literature regarding designs that account for such effects in medical research, and consider the appropriateness of these designs to health education research. To illustrate the application of a preference design to health education research, we present analyses using process data from a mixed RCT/preference trial comparing two formats (Group or Self-Directed) of the "Women take PRIDE" heart disease management program. Results indicate that being able to choose one's program format did not significantly affect the decision to participate in the study. However, women who chose the Group format were over 4 times as likely to attend at least one class and were twice as likely to attend a greater number of classes than those who were randomized to the Group format. Several predictors of format preference were also identified, with important implications for targeting disease-management education to this population.