Objectives. This article analyzes the causal relationship between political regime dynamics and social insurance expansion. I theorize that the social insurance expansion is the result of the ruling elites' strategic decision about regime change to dispel revolutionary motives. The key testable implication is that social insurance expansion is more likely to happen under a democratic regime, which, in turn, is influenced by the threat of social revolution evinced by strike activities.

Methods. Using historical data on social insurance coverage from 12 European countries from 1880 to 1945, I test the hypothesis employing a treatment-effects model that endogenizes democratization.

Results. I find a positive association between social insurance expansion and democracy, controlling for other political mechanisms. Furthermore, I find that democratic transition is greatly influenced by the duration and intensity of strikes.

Conclusion. This study suggests that social insurance expansion requires a link between a threat of revolution and democratization.