“…For example, our data did not indicate significant gains in young EL's expressive vocabulary knowledge in English as indicated in the Barnett et al (2007) study. A plausible explanation for the lack of effects in English could be that (a) our intervention was shorter and less structured than the instruction in the Barnett et al study; (b) young ELs in our study might not have reached a level of vocabulary knowledge in their native language that would allow them to transfer this knowledge to English, confirming Cummins (1979) threshold level hypothesis suggesting that bilinguals need to come to a threshold in their native language to see differences in their second language; (c) vocabulary knowledge does not transfer as easily as other skills such as phonological awareness and decoding (Baker, D. L., Burns, Kame'enui, Smolkowski, & Baker, 2015;Bialystock, Luk, & Kwan, 2005); and (d) in order for transfer between two languages to occur, young EL's English vocabulary knowledge needs to be at a certain level of proficiency (Baker, D.L., Park, & Baker, 2013;Lindsey, Manis, & Bailey, 2003). Our findings, however, corroborate the findings by Cena et al (2013), where first grade Spanish-speaking students living in the U.S. who received a vocabulary intervention in Spanish, made significant gains in their vocabulary knowledge in Spanish.…”