The three essays that comprise my dissertation are drawn from a longitudinal field study of the work process innovation of sourcing professionals at a large multinational paper products and related chemicals manufacturing firm. The focus of this study is an examination of how characteristics of the work process innovation context impact enterprise system (ES) acceptance, rich ES use behavior and the resulting individual-level job outcomes realized by knowledge workers in a strategic business process. The ES, an enterprise sourcing application, was introduced to innovate the work processes of employees who perform the sourcing business process. Over a period of 12 months, we collected survey data at four points in time (pre-implementation, immediately following training on the new system; following six months of use; and, following 12 months of use) to trace the innovation process as it unfolded. The three essays that comprise my dissertation focus on three key gaps in understanding and make three corresponding key contributions. The first research essay focuses on the transition from an emphasis on behavioral intention to mental acceptance in mandatory use environments. This essay contributes to the technology acceptance literature by finding that work process characteristics and implementation characteristics are exogenous to beliefs about the technology and that these beliefs are important to understanding mental acceptance as well in mandatory use contexts. The second and third research essays emphasize the transition from lean use concepts to conceptualizing, defining and measuring rich use behaviors and show that use must be captured and elaborated on in context. This is pursued through the development of two rich use constructs reflective of the sourcing work context and the complementary finding of countervailing factors in the work process that may impede the positive impact of rich use behaviors on job benefits.