The question of why adult learners prefer particular course design patterns was studied. During fall 1981, 281 adult continuing professional education students at Cleveland State University and at several U.S. military bases in West Germany and Italy were studied. The research was based on two previous studies: one tested hypotheses generated from theories of adult learning, and the other investigated the relationships between learning preferences and sex, life phase, and learning styles. This third research phase employed both qualitative and quantitative methodologies. Using the Course Design Preference Survey, respondents selected a preference for course design from among five choice design elements and explained their preferences. In addition, respondents completed the Learning Style Inventory, which identifies preferred approaches to learning: the degree of activity versus reflection, and preference for abstract conceptualization versus concrete experience. Through a content analysis of written rationales provided by respondents, eight major reasons for learner interaction preferences were identified, as well as 15 combinations of reasons. Results support the idea that diversity of learner interaction preferences is a predictable and legitimate phenomenon in postsecondary education. (SW)