Many types of economic and social activities involve significant behavioral complementarities (peer effects) with neighbors in the social network. The same activities often exert externalities that cumulate in "stocks" affecting agents' welfare and incentives. For instance, smoking is subject to...

We exploit the randomized evaluation of a remedying education intervention that improved the reading skills of low-performing third grade students in Colombia, to study whether providing educational support to low-achieving students affects the academic performance of their higher-achieving...