The subject of this article is learning processes in public policies. Twenty-eight case studies in the areas of environmental, agricultural and health policy, which were part of the Swiss National Research Programme No 27, Effectiveness of public policies, were used as a basis for studying the way in which inter organisational learning processes unfold in different policy fields (stimuli, knowledge transfer, social processes etc), the learning paths and forms of learning which can be identified within these processes and the conditions under which social processes can become successful learning processes. (The study is fully reported in Knoepfel et al, 1997. Conceptual preparatory work can be found in Kissling and Knoepfel, 1993; Kissling et al, 1994; Kissling-Näf and Knoepfel, 1994a; 1994b.)