Equating is an essential tool in educational assessment due the critical role it plays in several key areas: establishing validity across forms and years; fairness; test security; and, increasingly, continuity in programs that release items or require ongoing development. Although the practice of equating is rooted in long standing practices that go back many decades, one of the driving forces behind this handbook has been the notion that a great deal of information about equating is unfamiliar to or not easily accessed by practitioners. This information appears in scholarly texts, professional journals, and other publications. It derives from the accumulated experiences of people who are trained and experienced in measurement and have highly technical understandings of the issues; however, even when expert consultants advise policymakers on equating-related matters, communicating the substantive significance of the technical concepts in a user-friendly manner is a challenge. Thus the primary aim of this handbook is to provide an abbreviated conceptual background of key concepts and describe some common equating issues. It also attempts to guide readers to taking the first steps toward viable solutions. This handbook is not an attempt to gather or present a collection of mathematical equations, charts, graphs, or statistical formulae as part of any technical analysis. In fact, the use of equations to explain concepts has been deliberately minimized and avoided whenever possible. The handbook's secondary aim is to provide state-level measurement professionals with a useful resource for communicating the rationale for equating decisions to policymakers and other stakeholders. This handbook can begin to bridge the gaps between various perspectives as they relate to equating by describing situations where psychometric and policy matters might interact. As such, it may be a starting point or guide for formulating solutions that are practical, feasible, and technically sound. (Individual chapters contain figures and endnotes.) [This report was prepared for the Technical Issues in Large-Scale Assessment (TILSA) and the State Collaborative on Assessment and Student Standards (SCASS) of the Council of Chief State School Officers (CCSSO).]