Book excerpt: While previous work suggests two competing explanations for the effect of labor market regulation on firms' demand for debt, our results reconcile both the “strategic use of debt” and “financial flexibility” view. Exploiting staggered changes to labor laws in 28 OECD countries, we find that the average causal effect of employment protection on firm financial leverage is close to zero but hides much heterogeneity depending on firm ownership structure. We posit that a regulatory-induced increase in labor power (i) gives a firm a strategic incentive to raise more debt, but also (ii) increases operating leverage and the risk of financial distress that could encourage firms with poorly diversified blockholders to react with a more conservative financial policy compared to widely-held firms. Examining non-financial, non-utility listed firms over a 20-year period, we find that higher ownership concentration mitigates the positive effect of labor power on financial leverage, making the relationship less positive or more negative. This result does not seem to be driven by pretreatment differences among firms and is robust against a wide variety of tests. Our results highlight the importance of considering ownership structure in studying firms' capital structure decisions.