Most Americans are aware that income inequality has increased in the last 30 years. Less well known is that income instability—how much families’ incomes fluctuate up and down over time—has also grown substantially. The Great Risk Shift (Hacker 2006; revised and expanded in 2008) documented a major post-1970s rise in family income instability and argued that it was one indicator of an increasing shift of economic risk from government and employers onto workers and their families. This Briefing Paper updates, improves, and extends these earlier estimates of rising family income instability and discusses potential causes and implications of this trend.