Online learning (eLearning) has become a global phenomenon as many organizations and educational institutions worldwide have entered the field in an attempt to enhance the students' experience of learning. While numerous studies have focused on the effectiveness and benefits of eLearning, few have focused on understanding and measuring the user experience and relating this to the actual student usage of the eLearning system. This study addresses this gap by conceptualizing and measuring the eLearners' experience from two integrated perspectives: (1) the learners' affective perceptions using the flow model and (2) the learners' technology acceptance using the Technology Acceptance Model. The integrated perspective proposes that the users' acceptance and the affective responses toward a particular system are two important factors in determining the users' intentional and actual behaviors, which in turn, influence user participation and engagement with the system. The data was collected in 2004 directly from 964 students using a Web-based eLearning system called CECIL (http://www.cecil.edu) at the University of Auckland. The conclusions drawn from the results of the study using a structural equation model support the use of the integrated model for investigating eLearner behavior. The research implications of our findings are discussed.