The Affordable Care Act broadens and strengthens the health insurance benefits available to consumers by requiring insurers to provide coverage of a minimum set of medical services known as "essential health benefits." Federal officials implemented this reform using transitional policies that left many important decisions to the states, while pledging to reassess that approach in time for the 2016 coverage year. This issue brief examines how states have exercised their options under the initial federal essential health benefits framework. We find significant variation in how states have developed their essential health benefits packages, including their approaches to benefit substitution and coverage of habilitative services. Federal regulators should use insurance company data describing enrollees' experiences with their coverage—information called for under the law's delayed transparency requirements—to determine whether states' differing strategies are producing the coverage improvements promised by reform.