How can we increase contributions to public goods—to get donors to give more to charity, citizens to vote, households to consume less energy, drivers to carpool, and patients to take all of their antibiotics? One of the best ways is to make contributions more observable.

Perception of peer rank, or how we perform relative to our peers, can be a powerful motivator.

Social norms messaging campaigns are increasingly used to influence human behavior, with social science research generally finding that they have modest but meaningful effects.