Bridging the science of measurement and the practice of applied behavior analysis (ABA), this is the first comprehensive guide to reliability, validity, and evidence-centered design within a behavior-analytic framework. Students and ABA practitioners will benefit from the text's real-world case studies and clear connections to the Behavior Analyst Certification Board's BCBA Task List. Readers learn not only how to select, use, and interpret function- and skill-based behavioral assessments, but also how to critically evaluate their quality and appropriateness using contemporary measurement theory. Facilitating ethical, data-driven decision making across clinical, educational, and research settings, the text includes chapter-opening objectives, end-of-chapter reflection and discussion questions, and a glossary.