As reported in Christopher Dickey's Securing the City: Inside America's Best Counterterror Force-The NYPD, {Simon and Schuster, 2009) for more than a decade New York City Police Department has devoted two deputy commissioners (of Counter-terrorism and of Intelligence) and more than one thousand officers to a post-9/11 inspired counter terrorism program. During the time that this program has been in place there have been a number of plots discovered, and several near misses, but no terrorist attacks recorded in New York. Is this a successful public program. Should a new administration continue to make this extraordinary investment? The question is, how do we valily and credibly measure the success of this program in particular, and how do we measure the success of prevention program in general?

While not new, the administration of Mayor Bill DiBlasio has set a record with the number of newly appointed commissioners pledging policies and programs aimed at prevention. The Commissioner of the Administration of Children's Services announced a commitment to preventing child abuse, the Commissioner of Homelessness is committed to preventing homelessness, the new Commissioner of NYPD has re-affirmed the commitment to preventing crime he brought to the job when he first assumed that position in the administration of Rudy Giuliani. These a just a few of the agencies in City government that have embraced prevention of problems, as opposed to reacting to problems after the fact, as part of their approach to their assigned missions. After twenty years of crime decline in NYC since prevention was proclaimed as the new approach, the claim of successful policing is still much disputed.

These current commitments follow on those of a variety of programs in the Bloomberg, Giuliani and Dinkins administrations. This record of prevention programs provides a fertile field in which to explore the challenges of measuring the success of prevention programs. A recurring theme of Mayor's Bloomberg's management approach was "if you cannot measure it, you cannot manage it." A corollary of this proposition is that programs whose performance is hard to measure are hard to managed.

Drawing upon the experience of managers of programs aimed at prevention in New York City government, and the literature on measuring the success of prevention programs especially in the field of public health this paper will attempt to ascertain the current best practices for the management of prevention programs in a policing, health, education, and social services. One anticipated finding is that the fields of performance measurement and program evaluation will have to work more closely together to empower public management of prevention programs.