Techniques for modeling significant locations are described. A significant location can be a location that is significant to a user of a mobile device for a variety of reasons. The mobile device can determine that a place or region is a significant location upon determining that, with sufficient certainty, the mobile device has stayed at the place or region for a sufficient amount of time. The mobile device can construct a state model that is an abstraction of one or more significant locations. The state model can include states representing the significant locations, and transitions representing movement of the mobile device between the locations. The mobile device can use the state model to provide predictive user assistance.