Book excerpt: Measurement in Health Behavior offers faculty, students, researchers, and public health professionals the information they need to improve their knowledge of instrument development and testing and their understanding of reliability and validity testing discussed in articles and reports. The book also helps improve students’ and professionals’ ability to conduct basic tests for reliability and validity and hones their skills in interpreting the results of data analysis. Based on data collected from the author’s more than ten years of research and program development, Measurement in Health Behavior provides realistic examples from the public health arena to clearly demonstrate the book’s concepts.