[1] In 1972, Selinker introduced the concept of interlanguage, which built upon Pit Corder's previous work on the nature of language learners' errors.
Corder's and Selinker's work became the foundation of modern research into second-language acquisition, and interlanguage is accepted as a basic principle of the discipline.
[2] After completing his PhD, Selinker moved to the University of Washington, where he became assistant professor of linguistics and director of English for foreign students from 1966 to 1975.
There he served a turn as Head of the Department of Applied Linguistics, taught second language acquisition and supervised student research – both undergraduate and postgraduate.
He first introduced interlanguage in his 1972 paper of the same name, which built on Pit Corder's 1967 article The Significance of Learners' Errors.