Five-Year Study of Proposition 227 Finds No Conclusive Evidence Favoring One Instructional Approach for English Learners

Palo Alto, Calif. – There is no conclusive evidence that one instructional model for educating English learners, such as full English immersion or a bilingual approach, is more effective for California's English learners than another, according to a five-year study of Proposition 227. The study, by the American Institutes for Research (AIR) in conjunction with WestEd, concludes that a variety of factors in varying school contexts influence English learner achievement.

"Effects of the Implementation of Proposition 227 on the Education of English Learners, K-12" was conducted for the California Department of Education under a mandate by the state legislature. Passed in California in 1998, the proposition requires that English learners be taught “overwhelmingly in English” through sheltered/structured English immersion programs during a transition period normally not to exceed one year, and then once they have acquired a working knowledge of English, transferred to mainstream English-language classrooms. The proposition contains a provision that allows students whose parents sign a district-provided waiver to be taught bilingually. California is home to nearly one-third of the nation's five million English learners.

Key findings from the study include:

  • Since the passage of Proposition 227, students across all language classifications in all grades have experienced performance gains on state achievement tests.
  • During this time, the performance gap between English learners and native English speakers has remained virtually constant in most subject areas for most grades.
  • That these gaps have not widened is noteworthy given the substantial increase in the percentage of English learners participating in statewide tests, as required by federal and state accountability provisions.
  • Limitations in state data make it impossible to definitively resolve the long-standing debate underlying Proposition 227 as to whether one instructional model is more effective for California's English learners than another. However, based on the data currently available, there is no evidence to support an argument of the superiority of one English learner instructional approach over another.
  • The likelihood of an English learner meeting the linguistic and academic criteria needed to reclassify them to fluent English proficient status after 10 years in California schools is less than 40 percent.
  • Interviews with representatives of schools and districts among the highest performers in the state with substantial English learner populations further supported the finding that there is no single path to academic excellence among English learners.
  • The factors identified as most critical to their success were: staff capacity to address English learners' linguistic and academic needs; school wide focus on English language development and standards-based instruction; shared priorities and expectations in educating English learners and systematic, ongoing assessment and careful data use to guide instruction.

“Proposition 227 was based on the premise of the superiority of a single approach. This study challenges that assumption,” says Tom Parrish of AIR's Palo Alto office. He is the Principal Investigator for the study and one of the coauthors. “Given the diverse learning needs of English learners, we recommend less emphasis on dictating specific methods, continuing on the more general path of rewarding school academic success and intervening in the case of failure wherever it occurs.”

Adds WestEd's Robert Linquanti, Associate Project Director and one of the coauthors: “Our findings suggest that it is not the language of instruction but rather the quality of instruction that matters most. We also found a number of ways that state and district education leaders can better support school administrators and teachers in helping English learners progress and succeed.”

The study recommends the following to improve the achievement of English learners:

  • California should identify schools and districts that are successfully educating English learners at all grade levels, and create opportunities for their peers to learn from them.
  • The state should ensure that students’ English learner status does not impede full access to core curriculum.
  • Schools should limit prolonged separation of English learners from English-speaking students to cases of demonstrated efficacy.
  • District leaders need to ensure that their plan of instruction for English learners is articulated across classes within grades, across grades within schools and across schools within the district.

María Pérez and Amy Merickel of AIR were co-Project Directors and co-authors of the study.

About AIR

Established in 1946, with headquarters in Washington, D.C., the American Institutes for Research (AIR) is an independent, nonpartisan not-for-profit organization that conducts behavioral and social science research on important social issues and delivers technical assistance both domestically and internationally in the areas of health, education, and workforce productivity.

About WestEd

WestEd, a national nonprofit research, development, and service agency, works with education and other communities to promote excellence, achieve equity, and improve learning for children, youth, and adults. WestEd has 15 offices nationwide, from Washington and Boston to Arizona and California. Its corporate headquarters are in San Francisco. More information about WestEd is available at

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