The Affordable Care Act attempts to improve the adequacy of health insurance by establishing a minimum standard for "essential health benefits" (EHB). This paper documents challenges faced by insurance companies and state officials in the development and oversight of new plans that meet the new EHB requirements. We find that most people will see little change in the number of benefits covered by plans, but some will gain benefits, such as maternity care, mental health, and prescription drugs, that have often not been covered. The study also finds that insurers are taking limited advantage of their flexibility to add and subtract benefits through substitution.