This paper investigates to what extent globalization and regional integration lead to increasing equity market interdependence. I focus on the case of Western Europe, as this region has gone through a unique period of economic, financial, and monetary integration. More specifically, I quantify the magnitude and time-varying nature of volatility spillovers from the aggregate European (EU) and US market to 13 local European equity markets. To account for time-varying integration, I allow the shock sensitivities to change through time by means of a regime-switching model. I find that these regime switches are both statistically and economically important. While both the EU and US shock spillover intensity has increased over the 1980s and 1990s, the rise is more pronounced for EU spillovers. In most countries, shock spillover intensities increased most strongly in the second half of 1980s and the first half of the 1990s. Increased trade integration, equity market development, and low inflation are shown to have contributed to the increase in EU shock spillover intensity. Finally, I find some evidence for contagion from the US market to a number of local European equity markets during periods of high world market volatility. Keywords: Volatility Spillovers, Regime Switching, Contagion, EMU, Financial Integration