Many OECD countries have amalgamated their municipalities during the last couple of decades. For decisions concerning future territorial rescaling, it is crucial to augment the previously inconclusive evaluative knowledge of the effects of mergers. This paper examines the effects of amalgamations conducted between 1998 and 2009 in the areas of public service delivery, local finance, administrative staff, municipal autonomy and local democracy. The data are obtained from two comprehensive surveys of all local secretaries (top civil servants) in Switzerland in 1998 and 2009. The analysis -based upon a comparison between a quasi-experimental and a control group -(partially) supports the hypothesis of a positive effect on public service delivery, the professionalization of staff and municipal autonomy. The effect on local finance is inconclusive, and negative effects on local democracy are not discovered in the framework of this study.