Substantial growth in the numbers of English language learners (ELLs) in the United States and Canada in recent years has significantly affected the educational systems of both countries. This article focuses on critical issues and concerns related to the assessment of ELLs in U.S. and Canadian schools and emphasizes assessment approaches for test developers and decision makers that will facilitate increased equity, meaningfulness, and accuracy in assessment and accountability efforts. It begins by examining the crucial issue of defining ELLs as a group. Next, it examines the impact of testing originating from the No Child Left Behind Act of 2001 (NCLB) in the U.S. and government-mandated standards-driven testing in Canada by briefly describing each country's respective legislated testing requirements and outlining their consequences at several levels. Finally, the authors identify key points that test developers and decision makers in both contexts should consider in testing this ever-increasing group of students.