This study applied components of Csikszentmhalyi’s flow theory to the Web-based Training (WBT) environment. Specifically considered were how the equivalence of a learner’s perceived challenges and skills for an activity can effectively predict the emergence of flow in the WBT environment. Also considered was the ability of flow dimensions — defined in flow theory — to predict and model the occurrence of flow during WBT activities. Over a period of about one hour, students (n=43) from a southwestern US university engaged in WBT learning activities pertaining to on-line coursework or self-study. A special Web-based software installed on the students’ computers sporadically reminded them to complete a series of on-line questionnaires which collected data on their flow experience, learning activities, and flow dimensions. The data collection method employed by this study is effectively an electronic, Web-enabled version of, and functionally equivalent to, the Experience Sampling Method (ESM) used in other flow studies. This study employed questionnaires used in prior flow studies to collect data regarding respondents’ flow experiences and flow dimensions, and developed an on-line instrument to collect data on students’ learning experiences based on instructional events found in computer-based lessons from Gagné. Significant findings (p<.05) from this study suggest that, …