OBJECTIVES To determine whether minors can successfully purchase alcohol online and to examine age verification procedures at the points of order and delivery. DESIGN A cross-sectional study evaluated underage alcohol purchase attempts from 100 popular Internet vendors. SETTING The study was conducted at the University of North Carolina at Chapel Hill, July 14-27, 2011. PARTICIPANTS Eight 18- to 20-year-old individuals participated. OUTCOME MEASURES Rates of successful sales to minors and use of age verification procedures at order and delivery were determined. RESULTS Of the 100 orders placed by the underage buyers, 45% were successfully received; 28% were rejected as the result of age verification. Most vendors (59%) used weak, if any, age verification at the point of order, and, of 45 successful orders, 23 (51%) used none. Age verification at delivery was inconsistently conducted and, when attempted, failed about half of the time. CONCLUSIONS Age verification procedures used by Internet alcohol vendors do not adequately prevent online sales to minors. Shipping companies should work with their staff to improve administration of age verification at delivery, and vendors should use rigorous age verification at order and delivery. Further research should determine the proportion of minors who buy alcohol online and test purchases from more vendors to inform enforcement of existing policies and creation of new policies to reduce youth access to alcohol online.