This book is a worthy contribution to the literature on social groups and agency. While challenging, its meticulous argumentation helps to recast the familiar notion of the group as a tightly defined and widely applicable concept.

• Introduction ; 1. Acting as a Group Member ; 2. The We-Mode and the I-Mode ; 3. Shared We-Attitudes ; 4. Joint Intention and We-Intention ; 5. Joint Social Action ; 6. Group Action and Group Attitudes ; 7. Cooperation ; 8. Social Institutions ; 9. Cultural Evolution of Cooperative Social Activities ; 10. Group Responsibility ; References