Principles and Practice
             in
             Second Language Acquisition
             Stephen D Krashen
             University of Southern California
     This is the original version of Principles and Practice, as published in 1982, with only minor 
     changes.  It is gratifying to point out that many of the predictions made in this book were 
     confirmed by subsequent research, for example, the superiority of comprehensible-input 
     based methods and sheltered subject matter teaching (Krashen, 2003), the inefficacy of error 
     correction (Truscott, 1996, 1999), and the "power of reading" (Krashen, 2004). Subsequent 
     research has also, in my opinion, confirmed that in footnote 5, chapter 3, option 3 is the 
     correct one, that we acquire vocabulary best through comprehensible input (Krashen, 1989; 
     2003).
     I have changed my position on only one issue: At the end of Principles and Practice, I suggest 
     the use of a form of deception -  students may think they are acquiring vocabulary or learning 
     subject   matter,   but   unknown   to   them,   they   are   acquiring   because   they   are   getting 
     comprehensible input at the same time. I now think it is very important to make a strong effort 
     to inform students about the process of language acquisition, so they can continue to improve 
     on their own.
     Krashen, S. (1989) We acquire vocabulary and spelling by reading: Additional evidence for 
     the input hypothesis. Modern Language Journal 73, 440-464.
     Krashen, S. (2003) Explorations in Language Acquisition and Use: The Taipei Lectures. 
     Portsmouth, NH: Heinemann.
     Krashen, S. (2004) The Power of Reading. Portsmouth, NH: Heinemann.
     Truscott, J. (1996). The case against grammar correction in L2 writing classes. Language
     Learning, 46 (2), 327-69.
     Truscott, J. (1999). What's wrong with oral grammar correction? The Canadian Modern 
     Language Review, 55(4), 437-56.
                   Introduction to the Internet Edition
     Copyright © 1982 Stephen Krashen
     All Rights Reserved. This publication may be downloaded and copied without charge for all 
     reasonable, non-commercial educational purposes, provided no alterations in the text are 
     made.
     First printed edition 1982 by Pergamon Press Inc.
     Print Edition ISBN 0-08-028628-3
     First internet edition July 2009
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     Acknowledgments                                                            
     I am indebted to many people who have helped me both directly and indirectly. I can only 
     mention a few of them here. Earl Stevick and Robin Scarcella kindly provided me with 
     detailed comments on nearly every aspect of the manuscript. I have also received a great 
     deal of useful feedback from John Schumann, John Oller, Adrian Palmer, Tracy Terrell, 
     Andrew Cohen, Steven Sternfeld, and Batyia Elbaum. I am sure this book would be much 
     stronger if I had followed all their advice. The task of writing this volume was made much 
     easier by the support and understanding of my family, my wife Eula, my children Deborah and 
     Daniel, and my parents Leo and Julia Krashen. I would also like to thank my colleagues in the 
     Linguistics Department at USC for their intellectual stimulation and encouragement. I 
     especially thank Larry Hyman, Edward Finegan, Eugene Briere, Elaine Andersen, Elinor 
     Ochs, Edward Purcell, John Hawkins, and Bernard Comrie.
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