Book excerpt: A comprehensive resource for assessment practitioners, this book provides step-by-step guidance for developing, administering, scoring, and validating a range of performance tasks, including literacy and other types of proficiency assessments. The authors explore how to establish the purpose of the assessment and how to develop scoring tools, train raters, reduce rater bias, review scores and report results, and use item-level and test-level analyses to optimize reliability and validity. Clearly written and well organized, the book includes many practical examples and accessible explanations of concepts and statistical procedures. It encompasses the breadth of applications of performance assessment today, from educational testing and the credentialing of professionals to research and program evaluation. User-friendly features include: *Checklists of activities to complete at each stage of a performance assessment *End-of-chapter questions to facilitate self-study *Annotated suggestions for further reading *A quick-reference glossary of terms *Examples drawn from multiple educational and professional licensure contexts