Does social recognition motivate prosocial individuals? We run large-scale experiments at Italy's main blood donors association, testing social recognition in social media and peer groups. We experimentally disentangle visibility concerns and peer comparisons, and study how exposure to different...

We estimate the effect of an increase in time cost on the return behavior of blood donors. Using data from the Australia Red Cross Blood Service, we ask what happens when pro-social behavior becomes more costly. Exploiting a natural variation in which donor wait times are random, we use the...