Concentration (the share of a market’s output produced by its largest firms) is a key proxy for measuring market competition. This column introduces a cross-country dataset to measure concentration at the industry level between 2000 and 2019. It captures both domestic production and international trade flows as well as business group linkages. It finds that the average concentration across countries increased by five percentage points between 2000 and 2019, with notable differences across geographic competition levels. These insights are important for understanding competition dynamics and informing antitrust and economic policies to foster a competitive environment.