This article suggests effective approaches to teaching English language learners in ways that can be of benefit to all students in mainstream middle and high school English classes. The five approaches described herein that mainstream ESL teachers can do to make assessments more accurate and reliable, as well as to address heterogeneity, are: (1) Learn about the literacy background of the students; (2) Be careful with the language of the questions and provide language accommodations when necessary; (3) Give time; (4) Consider performance-based assessment; and (5) Gather data about ELL students from multiple sources. (Contains 2 figures and 1 note.)