Routines, the habitual and predictable behavior patterns of an organization, play central roles in both maintaining organizational performance and in adapting such performance to changing conditions. Deadlines interact with routines in important ways in influencing the course of organizational adaptation. This paper examines the role of routines and deadlines in influencing change in a regulatory program. It describes the adaptation of routines in the Environmental Protection Agency's (EPA) water pollution and pesticide programs in response to pressures and deadlines imposed by Congress, the courts, and the White House. The programs analyzed offer contrasting glimpses of the effects of routines on organizational change. Routines may be collective and shared by the members of an organization or unique to the specific groups or subgroups within it. When the organization primarily has widely-shared routines, few options will be perceived; consequently, collective routines tend to blunt the impact of pressures for change. On the other hand, routines that become fragmented, diverse, and individual in the face of repeated external pressures may facilitate change.