Krashen on "mingling"

Comment posted on NY Times website, following "The Bilingual Debate Continued," By Sandra Tsing Loh

" longitudinal research has shown that English-learning children in the United States have a much higher success rate at mastering the higher language skills that will enable them to succeed on standardized tests if they mingle, daily, with native English-speaking children."
I am all for mingling, but I have been doing and reading research in bilingualism for several decades and I don't know of any studies that say that mingling with English-speaking children helps in the acquisition of academic language.
What the research does say is that a good bilingual program helps the development of academic English, and so does wide, recreational reading.
Stephen Krashen