We put together a unique panel of thousands of good‐level prices before and after the euro to compare the determinants and understand the evolution of goods price dispersion across Europe over time. We find that tradeability and nontraded inputs play a significantly smaller role for cross‐country price dispersion after the adoption of the euro, and for Eurozone economies as compared to European Union ones. We then compare the distributions of law‐of‐one‐price (LOP) deviations over time to understand how the degree of integration across European economies changed after the euro. Our tests reveal that the distributions after the euro are typically significantly different from those before, consistent with a greater degree of integration. Utilizing our unique panel data set to trace the location of individual goods in the distribution of LOP deviations, we ask how the price advantage or disadvantage evident in these price distributions evolves over time, and whether goods characteristics play a role for the persistence of these LOP deviations. LOP deviations for these goods are highly correlated over 5‐ or 10‐ year horizons, and correlations remain significantly high over longer horizons. These correlations are greater for homogeneous as compared to differentiated goods and vary across countries. Finally, for most of these European economies and goods, price advantage is typically revealed to be more persistent than price disadvantage.