This study investigated how performance on reading curriculum-based measurement (R-CBM) in Spanish is related to performance on R-CBM in English. Parallel process growth models and quantile regression analyses were used to examine the relations between initial benchmark scores and growth and the consistency of the relations across student reading skill levels. Initial benchmark scores and growth were strongly related across languages in most grades, and initial scores were less strongly related for students with low and high reading achievement, as measured by curriculum-based measurement in most grades. Rates of growth were evenly related across performance in fourth and fifth grades, but less strongly related for high-achieving students in second and third grades. Practical implications and future directions are discussed.