In addition to covering statistical methods, most of the existing books on equating also focus on the practice of equating, the implications of test development and test use for equating practice and policies, and the daily equating challenges that need to be solved. In some sense, the scope of this book is narrower than of other existing books: to view the equating and linking process as a statistical estimation task. The goal of this volume is to propose new equating models, to take theoretical statistical tools and apply them to the practice of equating in novel and useful ways, and to tie explicitly the assumptions made by.