Pressman & Wildavsky’s Implementation Model

… a core concept in Implementation and Delivery and Atlas107

Concept description

Leslie Pal (reference below) summarizes the early for implementation model set out by Pressman and Wildavsky (1973).

Pal describes the essence of the Pressman and Wildavsky model (p. 190):

“The book that arguably kicked off interest in implementation by policy analysts was by Jeffrey L. Pressman and Aaron Wildavsky. First published in 1973 (3rd ed., 1984), it had an appropriately pessimistic title: Implementation: How Great Expectations in Washington Are Dashed in Oakland: Or, Why It’s Amazing That Federal Programs Work at All, This Being a Saga of the Economic Development Administration as Told by Two Sympathetic Observers Who Seek to Build Morals on a Foundation of Ruined Hopes. The book examined an urban employment scheme, called the Oakland Project, announced in 1966. At the time, Oakland had an unemployment rate of 8.4 percent, concentrated among inner-city blacks. The program was to spend $23 million on a variety of public works projects and would be administered by the Economic Development Administration (EDA). As Pressman and Wildavsky pointed out, the Oakland Project enjoyed wide political support and was well funded, with monies in place. Yet three years later, only $3 million had been spent, most of that for a freeway overpass and architects’ fees. Why did the Oakland Project fail?

“From the beginning, “the success of the EDA program depended on agreement among a diverse group of participants with differing organizational objectives” (p. 30). The project had, at minimum, 15 different sets of actors, some within the same agency. They included, among others, five different sets from within the EDA itself: the Department of Health, Education, and Welfare; the Department of Labor; the U.S. Navy; the City of Oakland; and African-American community leaders. Beyond this there were all the private sector actors who were supposed to create jobs with the help of EDA funds. Levels of commitment, perceptions of urgency, and capacity varied enormously among these actors. Moreover, the implementation process was marked by a sequence of tasks that had to be completed or agreements struck before the process could move on. Pressman and Wildavsky called these “decision points” that required “clearance” by multiple sets of actors in order for implementation to go forward. They hypothesized that 30 decision points required a cumulative total of 70 clearances. Assuming an 80 percent probability of agreement on each clearance point, the chances of completion were one in a million. Even if one assumed an unrealistically high probability of 99 percent for each clearance, the odds for successful implementation were only about one in two. “However you look at it, the ultimate probability of success is very low” (p. 107).”

Mitigating factors

Pal sets out (p. 190-191) a number of factors that make successful implementation more likely than the original Pressman and Wildavsky model would imply:

“One might argue that the Oakland Project succumbed to the fragmentation that characterizes the American political system. It is true that parliamentary systems like Canada’s have a higher degree of executive dominance and institutional capacity to implement from the top down (Atkinson, 1993; Pal & Weaver, 2003). But Canada’s is also a federal system, which reduces the executive dominance to some degree at the centre. The other notable feature of the Oakland Project was the high consensus around it. In cases where principles differ, where problem definitions are widely divergent, or where actors have incentives to impede, delay, or frustrate, it could be expected that policies will face even greater odds against implementation.

“Fortunately, things are not so grim. Subsequent work has shown that the probability of successful implementation increases if one adopts assumptions that are plausible, but only slightly different from those held by Pressman and Wildavsky in their study. After all, things do get accomplished, however imperfectly. The Pressman–Wildavsky implementation model consists of a chain of statistically independent nodes or clearance points with an attached probability. Relax the model in five ways and the probability for clearance increases substantially (Alexander, 1989).

  1. First, it is unrealistic to assume that actors will make only one attempt at clearance. They may persist in multiple tries.
  2. Second, clearance points are not always independent; they might be packaged or bundled in ways so that one clearance ripples through several others.
  3. Third, there is a bandwagon effect at times where previous clearances increase the probability of future clearances. This momentum usually develops in threshold decisions where a certain number of agreements are necessary before a large payoff can be received, which puts pressure on holdouts. A good example is labour negotiations, where both sides try to “build momentum” on a series of minor issues before they tackle the larger ones.
  4. Fourth, program-reduction strategies may be used to shorten the decision chain. If the proposed program is being held hostage at one clearance point because of some feature that requires agreement from reluctant supporters, it is possible to cut out that component and proceed to the next decision point.
  5. Finally, one can assume higher probabilities of clearance than 99 percent in some instances, and this has a marked effect on overall clearance probabilities.” [number formatting added]

See also: Implementation Theory.

Atlas topic, subject, and course

The Study of Implementation and Delivery (core topic) in Implementation and Delivery and Atlas107


Leslie Pal (2014), Beyond Policy Analysis – Public Issue Management in Turbulent Times, Fifth Edition, Nelson Education, Toronto. See Beyond Policy Analysis – Book Highlights.

Alexander, E. R. (1989). Improbable implementation: The Pressman–Wildavsky paradox revisited. Journal of Public Policy, 9, 451–465.

Atkinson, M. (1993). Public policy and the new institutionalism. In M. Atkinson (Ed.), Governing Canada: Institutions and public policy (pp. 17–45). Toronto, ON: Harcourt Brace Jovanovich.

Pal, L. A., & Weaver, K. W. (Eds.). (2003). The government taketh away: The politics of pain in the United States and Canada. Washington, DC: Georgetown University Press.

Pressman, J. L., & Wildavsky, A. (1984). Implementation: How great expectations in Washington are dashed in Oakland: Or, why it’s amazing that federal programs work at all, this being a saga of the economic development administration as told by two sympathetic observers who seek to build morals on a foundation of ruined hopes (3rd ed.). Berkeley, CA: University of California Press.

Page created by: Ian Clark, last modified 12 April 2017.

Image: From cover of Pressman & Wildavsky book at, accessed 6 April 2017.