This thesis investigates how peasants regulated and shared forest resources in North Ostrobothnia during the seventeenth century where large-scale tar and timber production took place. The forests were owned as commons by peasant communities on village and parish level and became increasingly exploited during the century. The aim of the thesis is to demonstrate how the growing importance of forest resources affected the ability of peasants to govern and share forest resources in a sustainable way. Focus is therefore put on the institutional organisation of peasant communities and emphasises the complexity of how governance within village and parish communities developed. Three interrelated dimensions of sustainability are considered: ecological, institutional, and economic sustainability. The thesis also seeks to explain how burghers and Swedish state officials influenced this development. This is done by qualitatively and quantitatively analysing local district protocols, maps, and Swedish legislation. The thesis shows how peasant communities achieved balance between the three dimensions of sustainability. This ensured that they did not undermine the ecological underpinnings on which they depended, that their institutional organisation remained robust, and that they could make a living. This was possible through the prioritisation of rules and borders through collective action. The thesis also shows an increasing level of nestedness within peasant communities. This development was both enabled and inhibited by the peasants’ relation to burghers and Swedish state officials who became involved in the nestedness of peasant institutions.