I've posted before on the fact that many of our students have small vocabularies and that this hampers their reading comprehension. (You can read that post here.) By far the best way to increase your vocabulary is to read a wide variety of materials - particularly books or articles at a challenging reading level. I have also posted on the fact that it is difficult to get students to actually do this.
Vocabulary building needs to begin - well, from birth really. However, college bound students should consciously work on their vocabularies beginning no later than middle school. How can you get a reluctant reader to work on his or her vocabulary without reducing it to rote memorization? Comic books can be a great method. Calvin and Hobbes is a great comic series with some terrific vocabulary words in it. It appeals to everyone age 10 and up. The artist, Bill Watterson, has retired, but compilations of the strips are still in print. You can also find them online.
I recently discovered another great vocabulary-building book series. Stephan Pastis, who draws the nationally syndicated comic strip "Pearls Before Swine", has also written a series of books about an elementary school character, Timmy Failure. The series is aimed at students in late elementary school, but I have enjoyed them, and I'm 53. These chapter books are in the style made popular by the Diary of a Wimpy Kid series. "Pearls" doesn't tend to be filled with SAT-level words, so imagine my surprise and delight when I encountered the following in the first Timmy Failure book, Mistakes Were Made: rigorously, depiction, alleviated, stipulations, assent, prudent. And that was just the first 50 pages! Each book in the series is entertaining - a quick, easy read. Unlike Calvin and Hobbes, which some children would need to read with a dictionary, many of the words in the Timmy Failure books are defined by the characters as you go, although in both series you could get the basic gist of many words from their context.
These books make great holiday gifts! You can order them here: