Hours worked are fundamentally important for aggregate economic activity, yet canonical macroeconomic models fail dramatically at tracking its long-run trends. We develop an intuitive and tractable extension of the canonical model that decomposes trend hours into extensive and intensive margins via household-side employment-attainment costs and firm-side employment adjustment costs. Its predictions track very well the trend behavior of hours, and its two underlying margins, in the United States and a host of
OECD countries. Our framework is relevant for analyzing the long run labor-market effects of a number of factors such as productivity growth, and tax or labor-market reforms