For this report, researchers conducted a literature review to better understand how consumers make choices about health insurance enrollment and to assess how website design can influence choice when consumers select plans online. The team also considered how such factors as imperfect information and bounded rationality can influence consumers' health plan choices and whether errors in decisionmaking caused by information failures or bounded rationality can be reduced with better website design. In addition to conducting the literature review, the team reviewed 20 health insurance websites, including 14 websites operated by state-based marketplaces, four private health insurance websites, and two public health insurance websites (the Medicare Plan Finder [Centers for Medicare & Medicaid Services, undated (b)] and the California Public Employees' Retirement System website [California Public Employees' Retirement System, 2016]). In reviewing these websites, the team attempted to understand how the design of the sites might influence choices. After a review of the team's findings, the report concludes with a discussion about how websites could be improved to better support consumers' enrollment decisions. We conducted the literature review and the review of the websites in the spring of 2015. This report will be of interest to policymakers and industry experts involved in designing health insurance websites and researchers who are interested in consumer choice. The work was sponsored by the U.S. Department of Health and Human Services, Office of the Assistant Secretary for Planning and Evaluation. However, the views, opinions, and findings presented here are ours and should not be construed as official government positions unless so designated by other documents. Questions concerning this report can be addressed to Christine Eibner