Aim of study: To analyze the factors that motivate the sharing of a contribution to a common pool resource (CPR).Area of study: We obtained data from Galicia communal forests during 2013-2014. Material and methods: A survey among forest owners in which questions about decisions, mimicking those in public good games, were included. In addition, the compliance with the principles of collective action (PCA), and their implications in the management of CPR were tested.Main results: PCA are not functioning perfectly in our sample of communal forest owners. In line with previous literature, results suggest that individuals are willing to share an important amount of endowment in a CPR. Examining the role that PCA play in individuals’ decisions, it was observable that when owners face the sharing of an endowment, the monitoring, conflict resolution mechanism and minimal recognition of rights imply more cooperative results. Current communal forests should promote a better application of these PCA in order to obtain a more cooperative behavior from their members.Research highlights: Communal forest owners are quite generous according to the results obtained. In addition, it has also been found that the endowment is an important factor to consider, while social aspects represented through the PCA also matter when explaining sharing decisions. The present study may be useful in order to promote stronger cooperation in local communities.