The purpose of test directions is to familiarize examinees with a test so that they respond to items in the manner intended. However, changes in educational measurement as well as the U.S. student population present new challenges to test directions and increase the impact that differential familiarity could have on the validity of test score interpretations. This article reviews the literature on best practices for the development of test directions as well as documenting differences in test familiarity for culturally and linguistically diverse students that could be addressed with test directions and practice. The literature indicates that choice of practice items and feedback are critical in the design of test directions and that more extensive practice opportunities may be required to reduce group differences in test familiarity. As increasingly complex and rich item formats are introduced in next-generation assessments, test directions become a critical part of test design and validity.Introducing new or unfamiliar item formats to examinees poses particular challenges to test developers because of the need for students to quickly and accurately understand what the test items require (Haladyna & Downing, 2004;Lazer, 2009). Item formats are defined not only by their response modes (e.g., multiple choice, constructed response) but also by the types of demands they are expected to place on an examinee's knowledge and cognition (e.g., basic arithmetic, scientific reasoning; Martinez, 1999). When introducing new item formats, the critical challenge is how best to introduce the task so that all students are able to respond to the format as intended by the test developers.With new innovations in achievement testing, especially through computer-based testing and performance assessment, novel item formats are increasingly being introduced to achievement tests to increase construct representation and measure more complex and authentic thinking