The authors were asked to find out whether "On Our Way to English" ("OWE"), a supplementary, text-based product to help elementary school students learn to read and speak English was more effective in a California and a Texas school district than the materials the districts already had in place. They conducted an experiment during the 2003-2004 school year. In the California study, a total of 384 English learners and 29 teachers participated. This included 6 bilingual classes and 21 immersion classes. In the Texas study, a total of 169 students and 20 teachers participated. This included 7 bilingual and 13 immersion classrooms. The findings from the two settings were similar: "OWE" is generally as effective as the control programs for reading proficiency and is generally more effective than control in improving oral proficiency. In California the value of "OWE" in promoting oral proficiency was greater in the immersion setting. In that setting, the effect was greater for the students starting with low proficiency. However, in the Texas district, where immersion students, were, for the most part, already proficient, the positive impact of "OWE" is observed for bilingual students. For the districts participating in this study, the authors' recommendation is to focus the use of "On Our Way to English" in the area of oral proficiency. (Contains 17 figures and 14 tables.) [Additional funding for this paper was provided by Harcourt Achieve. For research summary, see ED538440.]