Abstract: A method for determining the location of mobile devices, comprising providing at least one mobile device and at least two access points distributed over two or more locations; noting the identity of access points the device is connected to over time; noting transitions between access points a device is connected to and identifying two or more access points as belonging to the same location if the mobile device transitions between connecting to said access points within a certain time period; allocating a first location to a group of access points to which a device transitions within said certain period of time and a second or further location to access points to which a device does not transition to from the first set of access points within said certain period of time; thereby associating groups of one or more access points with one or more locations, and determining the location of the device when it is subsequently connected to one of the located access points.