Federal procurement looks like commercial contracting and is not. This article explains the structural differences that decide outcomes, beginning with the fact that the government's obligations come from regulation rather than negotiation, that clauses can be read into a contract that nobody wrote, and that the government can walk away from any contract at any time for its own convenience. It covers how competitions are actually structured and evaluated, why the evaluation record rather than the proposal decides protests, and the timeliness rules that eliminate more protests than the merits ever do. It then covers the claims process under the Contract Disputes Act and the certification requirement that converts an overstated claim into a fraud exposure, the changes and delay doctrines that generate most contractor recovery, and the cost and pricing rules that apply to money the contractor thought was its own. Later sections address the small business programs and the affiliation and subcontracting limits that disqualify unwary firms, and the compliance regime whose ultimate sanction is not damages but exclusion from the market entirely.