Objective classification systems are those in which classification decisions are based on explicitly defined criteria rather than subjective judgments. The objective criteria are organized into a classification instrument accompanied by operational procedures for applying the instrument to inmates in a systematic manner. The opening chapter of this handbook indicates the importance of evaluating classification and it reviews the most important studies conducted to date. Standards for conducting evaluations and ethical issues that must be considered in conducting research on human subjects are examined; process and impact evaluations and validation are briefly reviewed, along with data collection-methods. A chapter on evaluation goals considers impact, validation, and process evaluation goals as well as the selection of and standards for evaluation goals. A chapter on evaluation questions discusses the definition of, examples of, and standards for evaluation questions. An examination of evaluation designs and methods reviews types of evaluation design, evaluation methods, and standards for evaluation designs and methods. Remaining chapters feature discussions of evaluation measures, sampling, data collection, and statistical methods. Summary of evaluation standards, glossaries, and 64 references