The Affordable Care Act (ACA) created the Consumer Operated and Oriented Plan (CO-OP) Program to provide consumer-focused health insurance options. But the CO-OP experience to date reveals factors that limit market competition. This report considers the challenges that CO-OPs have faced through analysis of plan, pricing, and enrollment data for six CO-OPs. We also interviewed CO-OP executives and experts to better understand the market assumptions and strategies of these new companies. We describe how CO-OPs responded to the prohibition on using federal loans for marketing, problems associated with outsourcing health plan functions, CO-OP plan design and pricing strategies, dynamics of both high and low enrollment, and challenges related to the ACA's premium stabilization programs. We conclude by highlighting the role of federal and state policy decisions in adding to rather than reducing barriers to market entry for CO-OPs.