This document summarizes research on web-based distance education. It finds that while interest is growing, most research so far has been hypothetical, theoretical or descriptive rather than empirical. It reviews three categories of studies: developmental studies investigating strengths and weaknesses of online environments, evaluation studies of costs and benefits, and studies of student perception and performance. Examples discussed include studies of the design of virtual classrooms, cost modeling methodologies, and relationships between learning styles, strategies and outcomes.