Instructional systems, both distance education and campus-based, may be viewed in terms of intrapersonal and interpersonal "instructional dialogues," that mediate and facilitate learning respectively, and "instructional resources" that enable such dialogues. Resources include self-instruction texts, tutorials, instructor availability, websites and more. This study investigated the dialogic behaviour of 521 Open University of Israel students as they studied undergraduate courses in Exact and Natural Sciences, Social Sciences and Humanities. Research objectives were to document what dialogue types, mediated through which resources, were utilized by students to overcome conceptual difficulty while reading instructional texts and while working on assignments. Two main findings emerged: (1) initially, most students dealt with both kinds of conceptual difficulty individually, on their own; only when such efforts failed did they turn to interpersonal dialogue; and (2) most students turned to peers for help, not to their instructors. These findings conflict with the assumed importance often ascribed to interpersonal, instructor-student dialogue by some distance education theorists. (Contains 9 tables.)