Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for channel scanning. In one aspect, a method includes, while maintaining an association with a first access point on a first channel during first, second, and third consecutive time slices: (i) monitoring, by a client device, a single second channel during the first time slice and the third time slice, and (ii) monitoring, by the client device, the first channel during the second time slice; receiving a beacon from a second access point during the first time slice or the third time slice; and determining a property of the client device or the second access point using the beacon, without using the beacon to determine whether to establish an association with the second access point.