Abstract: In the textbooks, procedural due process is a strictly judicial enterprise; although substantive entitlements are created by legislative and executive action, it is for courts to decide independently what process the Constitution requires. The notion that procedural due process might be committed primarily to the discretion of the agencies themselves is almost entirely absent from the academic literature. The facts on the ground are very different. Thanks to converging strands of caselaw -- partly involving due process, partly involving judicial deference to agency interpretation of procedural provisions in statutes, and partly involving the long shadow of Vermont Yankee v. NRDC -- agencies themselves are now the primary front-line expositors and appliers of the cost-benefit balancing test of Mathews v. Eldridge. The courts for their part often defer, explicitly or implicitly, to agencies’ due process decisions. I will defend this approach, and urge that it be made fully explicit. Rather than decide for themselves “what process is due,” courts should ask only whether the agency offered a rational justification for providing whatever process it did provide. Although the Mathews cost-benefit calculus would still supply the rule of decision, courts should merely review the application of that rule by agencies, and defer to reasonable agency decisions about the costs and benefits of procedural arrangements.