It is more than a little humbling to find that a book one has spent much

of one’s professional career trying to write can claim to be no more than

an introduction. The ideas in it have developed over twenty years.

Whenever I can, I have said where they come from, but I am certain that

there will be many sources that I do not recall, notions and phrases I

have absorbed from reading and teaching and listening, and that I pass

on into the public domain of knowledge. I take this opportunity to

thank my teachers, colleagues, and students.

Apart from the longish incubation period, the writing of this book

took a number of years. An unexpected gap in a teaching programme

gave me the opportunity to prepare a dozen or so lectures on current

theories of second language learning; this later formed the basis for a

paper I was invited to give at the University of Wisconsin-Milwaukee

conference in 1985. From these initial notes, the book started to take

shape, but the bulk of the work of writing waited for a year’s leave from

Bar-Ilan University; without the sabbatical, I doubt that it would have

been finished.