Since 1980, the Swiss spatial planning law (RPG) demands that land be used economi-cally. However, the overall zoning and settled areas of Switzerland is still greater than that regulated by RPG’s article 15. In particular, in rural and tourist-dependent municipalities, the proportion of zoned building land is far greater than the official limitations. Against this background, the present article addresses two research questions. First, what are the driving factors and barriers for local municipalities to (not) reduce their zoning areas? Second, what factors does the political success of reducing building land reserves depend upon? Both questions are dealt with in an empirical study in three Swiss non-urban municipalities. The results show that local authorities are mainly motivated to reduce zoned building land if the superordinated cantonal authorities exert pressure upon them. Major success factors, when it comes to reducing building land reserves in local municipalities, are the cooperation with the superordinated (cantonal) agency or the communication skills of the local authorities with regard to the landowner. Henceforth, these success factors should be better taken into consideration in spatial planning in Switzerland.