Administrative agencies frequently say “not now.” They defer decisions about rulemaking or adjudication, or decide not to decide, potentially jeopardiz- ing public health, national security, or other important goals. Such decisions are often made as a result of general Administration policy, may be highly controversial, and are at least potentially subject to legal challenge. When is it lawful for agencies to defer decisions? A substantial degree of agency autonomy is guaranteed by a recognition of resource constraints, which require agencies to set priorities, often with reference to their independent assessments of the relative importance of national policies. Agencies frequently defer decisions because they do not believe that certain policies warrant prompt attention. Unless a fair reading of congressional instructions suggests otherwise, agencies may defer decisions because of their own judgments about appropriate timing. At the same time, agencies may not defer decisions—or decide not to decide—if (1) Congress has imposed a statutory deadline, (2) their failure to act amounts to a circumvention of express or implied statutory requirements, or (3) that failure counts as an abdication of the agency’s basic responsibility to promote and enforce policies established by Congress. Difficult questions are raised by moratoria, formal or informal, on regulatory activity, especially if they are motivated by political considerations. Difficult questions also arise when agencies cannot feasibly meet statutory deadlines while fulfilling their obligation to engage in reasoned decisionmaking.