A method and a system for the localization of a mobile WLAN client, located within a WLAN network of multiple WLAN stations. Static reference points are ascertained by measuring field strengths of the WLAN stations at spatial coordinates, aided by WLAN client(s), and assignment of the measured field strengths to the spatial coordinates in terms of data records. Self-learning ascertainment of further dynamic reference points is obtained by measuring field strengths of the WLAN stations, aided by WLAN client(s) moving through the region of the network, and assignment of the measured field strengths in terms of data records to the respective spatial coordinates calculated for this purpose, in the database server. This may be done to localize a WLAN client by selecting a plurality of nearest matched data records of static and dynamic reference points whose subsequently calculated center of gravity corresponds to the estimated position of the WLAN client.