Recent years have seen much discussion in the literature about the core of the IS field. While extreme positions in this debate see IS research either as purely technical or purely behavioral work, we believe that one area of competence and contribution for IS researchers lies at the boundary of technology and individual human psychology. In addressing this question, IS researchers frequently invoke psychological constructs at a high level of abstraction, in order to achieve theories that allow wide knowledge claims. We contend that this fails to provide operationalizable and actionable linkages between the IT artifact and the psychological user model: exactly that area that should represent the contribution of IS research. This paper addresses these shortcomings by urging researchers to focus on the "forgotten" constructs on the "left hand side" of the model, characteristics of the artifact that serve as antecedents to user behavior. We propose a theory template that can be used to instantiate specific theories. We illustrate this template by examining how it can be used to instantiate existing theories and develop new theories.