An Overview

1Improving and sustaining successful public health interventions relies increas-ingly on the ability to identify the key components of an intervention that are effective, to identify for whom the intervention is effective, and to identify under what conditions the intervention is effective. The published literature includes a plethora of reports about interventions that have successful outcomes. A limited number of studies, however, disentangle the factors that ensure successful out-comes, characterize the failure to achieve success, or attempt to document the steps involved in achieving successful implementation of an intervention. To truly advance science and our understanding of applied interventions, we must learn a great deal more about public health intervention successes and failures. Process evaluation efforts can assist in making these discoveries. In the last decade, the literature on process evaluation related to public health interventions has grown considerably. In the late 1990s and in early 2000, there has been an explosion in the number of published studies that include extensive process evaluation components. There are several plausible explanations for this noticeable increase in the use of process evaluation. Social and behavioral interventions have become increasingly complex, making it important for researchers to know the extent to which all intervention components are actually implemented. This complexity stems from the fact that projects are often imple-mented at multiple locations, so that process evaluation becomes essential for en-suring that planned interventions are carried out equally at all sites. Complexit