This paper examines the empirical link between labor market institutions and international business cycle synchronization. Using a data panel of 20 OECD countries over the 1964–2003 period, we evaluate how cross‐country labor market heterogeneity affects business cycle comovement. Our estimation strategy controls for a large set of possible factors influencing cross‐country GDP correlation, which allows a comparison of our results with those found in previous studies. We find that bilateral trade, trade similarity, monetary and fiscal convergence, as well as EMU membership lead to more synchronized cycles. Our results show that labor market regulations affect the extent of business cycle synchronization. Disparities in employment protection laws and direct taxation tend to lower international comovement while divergence in union density, unemployment benefits, and indirect taxation enhance cross‐country correlations. The level of labor market regulations also matters. Heavier employment taxes are found to raise GDP comovement.