A difficult task in creating rich, exploratory interactive learning environments is building an environment that is truly engaging. Engagement can be defined as the nexus of intrinsic knowledge and/or interest and external stimuli that promote the initial interest in, and continued use of a computer-based learning environment. Complete and total involvement in a given task is described by Csikszentmihalyi's Flow Theory. Flow Theory defines the difference between enjoyment and pleasure; an optimal experience is more of a manifestation of the former. The following elements of flow are manifested in computer games and learning environments: (1) task that can be completed; (2) ability to concentrate on task; (3) task has clear goals; (4) task provides immediate feedback; (5) deep but effortless involvement; (6) exercising a sense of control over actions; (7) concern for self disappears during flow, but sense of self is stronger after flow activity; and (8) sense of duration of time is altered. The quality of multimedia assets such as images, sounds, and animations, are a key factor in interesting users in a computer game; this is an important issue in the design and development of educational software. A table shows the relationships among flow, games, and design of computer-based learning environments. Contains 14 references. (AEF)