The introduction of enterprise-wide systems requires users to simultaneously adjust to both the new system’s requirements and changes associated with modified business processes—an adaptation that often goes beyond conspicuous behavioral elements. Therefore, to investigate the underlying attributes that characterize user interaction with and adaptation to information technology (IT), we collected data from four organizations that had implemented enterprise-wide systems for at least three years prior to commencing fieldwork. By taking a grounded theory approach, we identify four distinct adaptation patterns: reluctant, compliant, faithful, and enthusiastic. These patterns represent configurations of five interrelated attributes that users espouse in their interaction with enterprise-wide systems: attitude towards the system, approach to learning how to use the system, level of interaction with the system, exploration of system features, and stance towards changing work practices. We propose an emergent, substantive theory of IT adaptation patterns that explains the intricate interplay of individual, task, and organizational initiatives in shaping these adaptation patterns.