Book excerpt: An increasing number of employers are introducing workplace health promotion programs with the expectation that these programs will improve employee health, lower healthcare spending, and increase worker productivity as a by­product of workers remaining healthy or becoming healthy. As more resources are directed toward health promotion programs, the need for effective program evaluation, supported by necessary data collection, is paramount. This workbook provides a practical measurement and evaluation guide for health promotion program managers and external evaluators. The purpose of the workbook is multifold. For program managers not trained in advanced statistical methods and evaluation research, the workbook illustrates the complexity of conducting studies and provides tools and guidance to assist in their evaluation efforts. For readers with advanced training in program evaluation, the workbook illustrates how techniques and principles used in other applied research studies can be adapted to workplace health promotion. This workbook, an update of the prior Program Evaluation chapter published in the third edition of O'Donnell's Health Promotion in the Workplace, places a greater emphasis on describing the three components of program evaluation: structure, process, and outcomes, with a particular focus on economic evaluations of worksite programs- specifically methods employed for conducting cost/benefit evaluations, otherwise known as return­on­investment (ROI) studies.