In this brief, we use a national representative sample of ever-English learners (N = 783) to examine relations between English learner concentration within classrooms and reading growth between Kindergarten and Grade 5. Piecewise growth models were used to estimate relations for four developmental periods (K-1, Grade 1-2, Grade 2-3, and Grade 3-5). Results indicated non-significant, trivially sized relations for classroom English learner concentration across periods, with and without controls for school concentration and student characteristics. Results were robust across multiple specifications. Findings call into doubt the academic benefits of the common practice of grouping English learners together in particular classrooms. [This paper will be published in "Educational Researcher."]