Rulemaking gives agencies significant power to change public policy, but agencies do not exercise this power in a vacuum. The separation of powers system practically guarantees that, at times, agencies will be pushed and pulled in different directions by Congress and the president. We argue that these forces critically affect the volume of rules produced by an agency. We develop an account of agency rulemaking in light of these factors and test our hypotheses on a data set of agency rules from 1995 to 2007. Our results show that even after accounting for factors specific to each agency, agencies do, in fact, adjust the quantity of rules they produce in response to separation of powers oversight. Further analysis shows that the president’s influence is limited to those agencies that he has made a priority.