Business and civic leaders, educators, and policymakers of all stripes share concerns over the relentless erosion of America’s middle class and growing polarization of incomes. Most decry the loss of middle-class jobs and fear the corrosive effects such trends might wreak on the nation if left unchecked. At the heart of the issue is an oft-discussed anomaly: while millions of aspiring workers remain unemployed and an unprecedented percentage of the workforce report being underemployed, employers across industries and regions find it hard to fill open positions. The market for middle-skills jobs—those that require more education and training than a high school diploma but less than a four-year college degree—is consistently failing to clear. That failure is inflicting a grievous cost on the competitiveness of American firms and on the standard of living of American workers.