Occupational Skill Premia around the World. Richard Freeman, 2020, Paper, "Firms hire workers to undertake tasks and activities associated with particular occupations, which makes occupations a fundamental unit in economic analyses of the labor market. Using a unique set of data on pay in identically defined occupations in developing and advanced countries, we find that occupational pay differentials narrowed substantially from the 1950s to the 1980s, then widened through the 2000s in most countries, creating a U-shaped pattern of change. The narrowing was due in part to the huge worldwide increase in the supply of educated workers. The subsequent widening was due in part to the weakening of trade unions and a shift in demand to more skilled workers associated with rising trade. The data indicate that supply, demand, and institutional forces are all drivers of occupational differentials, ruling out simple single factor explanations of change. The paper concludes with a call for improving the collection of occupational wage data to understand future changes in the world of work."