Most behavioral models used in information systems (IS) research have focused primarily on the role of conscious intentions in determining whether users will adopt or continue using a particular IS. Only recently have IS researchers begun exploring subconscious, automatic predictors of behavior such as habit. Perhaps the biggest constraint has been the lack of a universally accepted, theoretically based, and valid measurement instrument for the study of this complex psychological phenomenon. This paper builds on recent advances in the understanding of habitual behavior from social psychology, by proposing the development of an improved habit measure to be applied in an IS setting. The validated measure will then be used to examine how habit can counteract intentions and inhibit the adoption and use of systems that have been deemed important to a company’s success. Specifically, we hypothesize that habitual use of an existing system will negatively impact both intentions to use, and actual usage of, a new system. By better understanding habit’s inhibiting influence on IS acceptance, strategies can be developed for the specific purpose of breaking these preexisting habits, and encouraging the development of new ones.