Aggregate and sectoral comovement are central features of business cycles, so the ability to generate comovement is a natural litmus test for macroeconomic models. But it is a test that most models fail. We propose a unified model that generates aggregate and sectoral comovement in response to contemporaneous and news shocks about fundamentals. The fundamentals that we consider are aggregate and sectoral total factor productivity shocks as well as investment-specific technical change. The model has three key elements: variable capital utilization, adjustment costs to investment, and preferences that allow us to parameterize the strength of short-run wealth effects on the labor supply.

We investigate the consequences of demographic change for business cycle analysis. We find that changes in the age composition of the labor force account for a significant fraction of the variation in cyclical volatility observed in the G7. Since World War II, these countries have experienced dramatic demographic changes, although details regarding timing and nature differ across countries. We exploit this variation to show that the workforce age composition has a large and significant effect on cyclical volatility. We relate our results to the recent decline in US macroeconomic volatility, finding that demographic change accounts for approximately one-fifth to one-third of this moderation.