Today, hundreds of Federally-funded drug and alcohol-focused community coalitions operate across the United States, joined by many others that rely primarily upon state or private funding. The watchword these coalitions share is prevention, and the overriding challenge they live for is to offer effective support for our nation’s youth in living a healthy and drug-free lifestyle. At conferences, in online events, and in our work with such coalitions, there is a key question on everyone’s mind: “What preventive strategies work most effectively in our distinctive community, and how do we know whether we are succeeding?” As an evaluator, I think those are great questions. Really, they comprise the bottom line for any strategic effort. I also believe that these coalitions are in an excellent position to answer these questions—not in the abstract, but in terms of their own community, their own neighborhoods, and the youth they know and seek to serve. It is possible to discover what works—and what doesn’t work—to achieve a particular prevention goal in a particular community. I believe this for two reasons. […]