The U.S. General Services Administration (GSA) opened a new chapter in public procurement by awarding three contracts—to Amazon Business, Overstock.com, and Fisher Scientific—that will allow federal users to buy directly from online electronic marketplaces, with sales anticipated to total $6 billion annually. This proof-of-concept effort, dubbed the “commercial platforms” initiative by GSA, marks a radical departure from traditional procurement practices because it will allow individual Government users (not necessarily procurement officials) to make “micro-purchases” (generally up to $10,000) using Government purchase cards. By removing the federal procurement system as an intermediary in the purchasing process, and in essence outsourcing the selection of available sources to private providers of electronic platforms, GSA’s initiative has both reshaped procurement and potentially redrawn a marketplace. This paper reviews the purpose and history of GSA’s commercial platforms initiative, which began with a mandate from Congress to explore electronic commerce options and evolved through long exchanges with industry, users, and other stakeholders. In assessing the reasons for the initiative, the paper notes a longstanding concern (framed by principles of agency theory) that users’ needs were not being met by the traditional procurement system. The paper discusses GSA’s decision to steer the initiative to existing commercial platforms and reviews key elements of the solicitation used to frame the “no-cost” contracts with the online marketplaces. Because Amazon Business was by far the most prominent of the awardees—indeed, Amazon had played an ongoing role in pressing for the procurement—and vendors may want to sell through the commercial platforms to reach federal customers, this paper focuses on Amazon Business’ procedures in discussing how vendors might join the commercial platforms. The paper concludes with a series of Guidelines that vendors and other market participants might use, as they enter this new corner of the federal marketplace.