This paper first summarizes two central debates in the field of social scientific Internet research, namely the debate about the so-called `social impact of Internet use' and the debate about the existence of community on the Internet. Early research discussed whether building up a community on the Internet was possible and what the e®ects of the use of the Internet were for its user. Recent research on the social consequences of Internet use suggests that `the' Internet should no longer be regarded as a constant that has uniform e®ects for its users. Rather, the consequences of its use depend on a number of contextual conditions. The paper presents some theories that explain which conditions and features of online groups facilitate the ¯nding of solutionsto bilateral or group-level problems of cooperation.