Achieving the promised benefits of a new technology is closely tied to its sustained use. The dominant approach has been to predict use based on behavioral intention. Central to this approach is the assumption that use comes from conscious decision making, resulting from “thinking”, “reflecting”, and “cognition”. However, related work has shown that, over time and with increasing experience, use becomes habitual (routine, automatic) and when this happens, it is not subject to conscious decision making. This paper extends the technology adoption and use literature by testing the relative effects of intention and habit as determinants of use. We conducted a longitudinal field study over the period of one year, with 4 points of measurement in 7 organizations among 1235 users, to examine the effects of intention and habit from the formative stage of experience with a new technology through to an established, stable stage. The results provided strong support for habit as a predictor of use, especially over time, as use became well-rehearsed, and habit was a stronger determinant of use than intention was. In fact, habit dominates intention as a predictor of use, as experience increases. We discuss key implications for research and practice.