Introduction to the 2009 Internet Version:
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.