The complex nature of digital libraries calls for appropriate models to study user success. Calls have been made to incorporate into these models factors that capture the interplay between people, organizations, and technology. In order to address this, two research questions were formulated: (1) To what extent does the comprehensive digital library user success model (DLUS), based on a combination of the EUCS and flow models, describe overall user success in a prototype digital library environment; and (2) To what extent does a combined model of DeLone & McLean's reformulated information system success model and comprehensive digital library user success model (DLUS) explain digital library user success in a prototype digital library environment? Participants were asked to complete an online survey questionnaire. A total of 160 completed and useable questionnaires were obtained. Data analyses through exploratory and confirmatory factor analyses and structural equation modeling produced results that support the two models. However, some relationships between latent variables hypothesized in the model were not confirmed. A modified version of the proposed comprehensive plus user success model in a digital library environment was tested and supported through model fit statistics. This model was recommended as a possible alternative model of user success. The dissertation also makes a number of recommendations for future research.