He is best known for his innovative work on problems of collective action, cooperation, social movements, compliance-gaining behavior, adolescence and religion.
Between 1979 and 1981 Marwell (with his students) published four major articles titled “Experiments on the Provision of Public Goods by Groups, I – IV” in which he developed the “Cooperation Game,” variations of which would become standard in Economics for experimental work on free riding.
Furthermore, the ability to communicate and make bargains within real groups allowed cooperation to develop where theory had predicted total free riding.
Marwell's theoretical work on collective action was informed by his previous research on white students who participated in the Civil Rights Movement.
With N.J. Demerath, III and Michael T. Aiken, Marwell conducted surveys of volunteers for the 1965 SCLC voter registration and organization drives in the South both before and after their summer experiences.
When Rodney Stark and his colleagues claimed that at least an important part of the strength of evangelical religion could be attributed to conversions of individuals seeking to leave the less collectively enthusiastic mainline Protestant churches, Marwell argued that the evidence was poor and that the use of free riding was theoretically weak.