Social identity theory has become increasingly important for economists. I discuss the contribution of Van Bavel and Packer's "The Power of Us" in light of what economists (especially experimental ones) can learn from their research.

The paper presents the results of a lab-in-the-field experiment in three South African townships located in the suburbs of Cape Town. The experimental design consists of a set of decisions on how the members of a naturally occurring group allocate an endowment to a private or to a public...