In 2006-2007, California revised its English language proficiency (ELP) assessment, the California English Language Development Test (CELDT), which resulted in more stringent criteria and higher cut scores for meeting proficiency. Using regression discontinuity designs and a difference-in-differences approach, this study examines the effects of the CELDT revision on students' academic achievements in Grades 2 through 6 English language arts and mathematics. This study uses data from a large urban school district in California and follows two cohorts of Spanish-speaking students initially classified in kindergarten in 2002-2003 and 2006-2007. The CELDT revision did not significantly change the effects of being initially classified as ELs on students' later outcomes. Before the change, being initially classified as ELs benefited students' Grades 2 and 3 outcomes. After the revision, the positive effects of EL classification tended to decrease, but the impact was not sufficiently significant.