The present article explores the concept of user involvement in the information system (IS) development context. It integrates situational involvement and intrinsic involvement constructs in the Technology Acceptance Model (TAM) and empirically tested a theoretical model with premises that were previously tested separately but not operationalized and tested together. From data collected from companies that have recently implemented an IS, Exploratory Factorial Analysis (EFA), Factorial Confirmatory Analysis (CFA), and Structural Equation Modeling (SEM) were used to assess the construct's validity and the hypothesis test of the model, respectively. With a sample of 114 respondents, the main results indicate that situational involvement influences intrinsic involvement, perceived usefulness, and ease of use perception; it also indicates that intrinsic involvement influences usefulness perception, ease of use perception, and behavioral intention. Thus, this paper validated the assumptions about the importance of user involvement as an influence in adopting an IS, pointing out that situational involvement influences intrinsic involvement and that future users can become cognitively biased to better perceive a system as useful and easy to use, increasing its acceptance and adoption. It represents an original approach in this field with theoretical and empirical contributions.