<p>I'm pretty sure most word books and vocabulary lists are derived from previously administered SAT tests, the Blue Book, and/or similar sources. I have taken a couple practice tests, and have noticed that I know most words. So I'm I getting a false sense of confidence when I take practice tests, since I don't know what will pop up on the real SAT?</p>
<p>Depends what books you’re using 
If you’re doing great on the Blue Book you will probably be fine. Sentence completion is as much process of elimination as it is actually knowing the words anyway.</p>
<p>If you’re still concerned, check the vocab list in the yellow Gruber’s book as that has a very comprehensive list of the words that frequently appear on the SAT, and feel free to memorize them if that makes you feel better.</p>