Benefits of DL


Portland Public Schools (PPS) students randomly assigned to dual-language immersion programs outperformed their peers on state reading tests by 13 percent of a standard deviation in grade 5 and by 22 percent of a standard deviation in grade 8. DL programs improved reading in English, increased English proficiency for English learners, and proficiency in two languages did not come at the cost of performance in mathematics or science. 

Prior studies of DLI have shown that students in such programs perform as well as or better than their peers in core content areas such as English language arts, mathematics, and science—which are all typically tested in English— especially by mid-elementary school. However, those studies left open the question of whether the effects should be attributed to the DLI programs themselves or to the characteristics of the families and students who chose to enroll in those programs. The study focused on 1,625 students who were randomized to immersion or to a control group via Portland’s immersion pre-K and kindergarten immersion lotteries in 2004–2005 through 2010–2011. Further, the study was able to track the outcomes not only for lottery applicants who remained within PPS, but also for those who subsequently entered other public school districts in Oregon. 


Please read Massachusetts’ Fact Sheet on the, “Benefits of Dual Language Educational Programming” below. This fact sheet breaks down the associated benefits of dual language programming into categories and easily illustrates the importance of having dual language programs in our schools.