This is one of a series of 9 briefs comparing the early implementation experiences of the ACA in eight states: five that have chosen to aggressively participate in all aspects of the Affordable Care Act (ACA; Colorado, Maryland, Minnesota, New York, and Oregon) and three that have taken only a limited or no participation approach (Alabama, Michigan, and Virginia). This brief focuses on the implementation of the Small Business Health Options Program (SHOP) Marketplaces, which are new structured markets for the employer purchase of small group insurance for their workers.