Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
We examine the factors leading to creation and growth of national Old-Age Insurance (OAI) and Health Insurance schemes. None of the theories we test fit the data very well. There is weak evidence that the probability of adopting a system declines in a country's wealth and in the ethnic heterogeneity of its population. Catholic countries are more likely to create earnings-related OAI systems. The growth of OAI spending since 1960 has varied considerably across countries, with fast growth in countries emerging from dictatorship and non-English speaking countries. We conclude that social insurance can be politically expedient for many different reasons.