In this paper we examine whether collective action is consistent with larger carbon stocks per hectare in the community forests of Nepal. We also test whether collective action results in greater tree density per hectare, additional canopy cover and more regeneration measured as seedlings per hectare. Our main finding is that within the existing institutional environment, collective action broadly defined has very important, positive and large effects on carbon stocks and in some models on other generally aspects of forest quality. Depending on our measure of collective action, we are able to identify carbon effects at both the forest and plot levels, but especially at the plot level when plots are matched based on plot and forest characteristics. We also find that the Nepal Community Forestry Programme does not provide a unique path to forest health or carbon sequestration. Indeed, in several models CFs do no better than NCFs, while broader measures of collective action show consistent effects, particularly on carbon.