Sociologists typically assume that immigrants'
acquisition of English as a second language follows the
opportunities and motivations to become proficient in English,
while many linguists argue that second language acquisition
may be governed by maturational constraints, possibly biologically
based, that are tied to the age at onset of language learning.
In this article, I use U.S. census data to investigate
the relationship between age at onset of second language
learning and levels of English language proficiency among
foreign-born adults in the United States. The overarching
conclusion is that proficiency in a second language among
adults is strongly related to age at immigration. Part
of that relationship is attributable to social and demographic
considerations tied to age at entry into a new country,
and part may be attributable to maturational constraints.
Many colleagues, spread across
several disciplines, provided valuable comments on this research.
Among them were Cynthia Fisher, Nancy Garrett, Susan Gonzo,
John Hagan, Charles Hirschman, Tim F. Liao, Michael Long, John
Mardeen, Madonna Harrington Meyer, C. Gray Swicegood, and Jack