When the Patient Protection a

nd Affordable Care Act (ACA) was signed into law in 2010, many groups projected how many people would enroll in health insurance plans satisfying the law’s new rules and requirements (ACA plans). Nearly six years later, enrollment in health insurance exchange plans is far short of initial projections, particularly for people who earn too much to qualify for subsidies to reduce high ACA plan deductibles. The dearth of exchange enrollees with at least a middle-class income indicates that the individual mandate is not motivating as many people, particularly younger, healthier, and wealthier people, to purchase coverage as was originally expected. Large insurer losses on ACA plans show that the overall risk pool is sicker and much more costly than originally projected, and are an indication that the law may require significant revision in order to avoid causing an adverse-selection spiral.