This book presents an investigation by research into the ways in which distance learning is affected by the physical design of printed study materials. In particular, it examines the use of engineering drawing systems for illustrated, instructional texts concerned with technical aspects of infrastructure development. Part I comprises a review of literature on learning and adult education, international development and distance learning, information design for self-instruction, and research into illustration, with particular reference to the visual perception of engineering drawings and the implications for their cross-cultural use. Part II presents questions and hypotheses which emerged from the literature review. It also presents the research methodology designed to test comprehension of engineering drawing systems, along with the results of tests undertaken by five adult learning groups selected from pre-degree, undergraduate and postgraduate populations. Part II concludes with an analysis and discussion of the results of these tests. Part III presents the conclusions drawn from both the literature review and from the analysis of the research results.It concludes with proposals for further study.