This paper reports on the first phase of a research project undertaken by a team at the University of South Australia and Victoria University of Wellington (New Zealand) to design and deliver educational applications of digital learning media and to identify criteria for assessment of the efficacy and quality of the use of such media from a comparative analysis of three credit-bearing courses delivered in both on-line and conventional modes of delivery. The paper examines a set of assumptions derived from a constructivist approach to learning design in the context of a case study of Infotrain, an Internet-based course on electronic publishing. The following design principles for production of educational applications of digital multimedia are outlined: foster critical thinking as well as core skill competencies; create problem-based learning modules; frame problems in learner's life context; non-linear problem sets; essential role of the mentor; making optimal use of digital storage potential; making optimal use of the unique random access characteristics of digital media/hypertext; foster navigation skills and access to the totality of resources available; no preferred solution path; and a guide through the labyrinth. The Infotrain case study and conclusions to be considered in design of new courses incorporating digital media are presented. (Author/DLS)