The purpose of this paper is to provide an estimate of the size of the Third Sector in European Union member countries and Norway. The conceptual framework for defining the Third Sector has been developed by a team of European experts working under the auspices of the Third Sector Impact project, and outlined in Salamon and Sokolowski (2016).

This conceptual framework covers all uncompensated efforts outside of organizations of any kind that benefit general public, performed by individuals 15 years of age or older, such as helping friends or neighbors, working for the benefit of communities, human rights, or the environment, except uncompensated internship, apprenticeship, and similar training activities to obtain occupational skills.

Previous research (Salamon et. al. 2004) has identified the following four dimensions describing the Third Sector that allow us to compare it to other segments of national economies and to its counterparts in different countries:

1. The size of the Third Sector workforce
2. The composition of the Third Sector (TS) workforce
3. The composition of TS revenue
4. The institutional composition of the TS

It must be noted, however, that the estimates of the size and contours of the European third sector offered here are necessarily highly preliminary. This is so because the data available on the key components of this sector remain grossly incomplete and, even where available, seriously out of date. While preliminary, however, the data presented here offer a solid first approximation of the scale and contours of the European third sector based on the best data available and estimating techniques available.