This article is about diffusion processes behind the innovation of sub-national energy policy measures in a federal system. Typically for the federal political system in Switzerland, the elements of the energy policy field are shaped by the principle of subsidiarity. The aim is that cantons promote innovative problem solutions and regionally adapted implementation. For this reason, policy differences between cantons are large and create a need for coordination. More concretely, I will analyze the impact of inter-cantonal institutions on different innovations in the field of energy policy. The research question is approached with an event history analysis on three different innovative measures in the Swiss cantons from 1990 to 2007. A more comprehensive picture of diffusion in one policy field is drawn with this approach. The main contribution of this paper is the finding that intergovernmental institutions promote diffusion in one policy field only for measures with certain characteristics. The internal determinants are therefore not a sufficient explanation. (C) 2010 Elsevier Ltd. All rights reserved.