Extended time is among the most common testing accommodations given to students with a wide range of disabilities. However, although school psychologists are often involved in accommodation decisions, many are unaware of research from the past decade that has changed their understanding of extended time. Used properly, testing accommodations let students demonstrate their skills, increasing the accuracy of their test scores. But accommodations are a double-edged sword: They break the standardization of testing, and so they can compromise score quality as well. Extended time is no exception to this rule. In this article, the author has selected the most important and consistent findings from the research literature, focusing on their relevance for practitioners. Four basic facts about this accommodation are of particular importance: (a) extended time often helps students regardless of their disability status; (b) it can change the proper interpretation of students' test scores; (c) decisions about it are not made consistently; and (d) interventions may help to decrease students' reliance on it.