Boards of directors are a vital part of corporate governance systems. In the on-going discussion about the development of national corporate governance systems, however, little interest has been given to the issue of how and why board behavior changes over time. In this article, we use an institutional approach and study the development of board behavior in Sweden between 1994 and 2004 and if it is affected by board composition and board network characteristics. In order to do so, we introduce the constructs of board activities, i.e. what the boards do, and board involvement, i.e. when in the decision process they get involved. Findings show that range of board activities and board involvement have increased drastically during this period, which indicates a change in the logic of appropriateness of Swedish board behavior. There are robust indications that new types of actors affect activities and involvement positively, as do board interlocks, whereas network centrality affects activities and involvement negatively.