We examine how changes in property rights security impact firm capital structure decisions by exploiting a quasi-natural experiment, specifically, the implementation of China's Property Rights Law in 2007 (the Law). Using a large dataset of non-listed firms and a difference-in-differences (DID) design, we examine the Law's cross-sectional heterogeneous effects on firm leverage. We find that financially constrained firms exhibit a significant increase in leverage relative to unconstrained firms after the Law's implementation. Our results are robust to three alternative measures of financial constraint: asset tangibility, ownership structure, and firm size. This finding is consistent with the financial constraint hypothesis that states that lenders are willing to extend more credit to constrained firms given that the Law strengthens creditor rights . Overall, we find that the Law has had a significant impact on firm leverage decisions and that it is particularly important to financially constrained unlisted firms. • The enactment of China's Property Rights Law of 2007 has heterogeneous effects on leverage decisions • Firms with low asset tangibility exhibit a significant increase in leverage relative to firms with high asset tangibility • Private firms exhibit a significant increase in leverage relative to non-private firms • Small and medium-sized firms exhibit a significant increase in leverage relative to large firms • The Law influences leverage choices differently in listed versus unlisted firms