The Mastery textbooks introduce intermediate-level ESL/EFL students to the most frequently used words in academic environments, based on the 800-word University Word List developed by Xue and Nation. Adding this academic vocabulary to the 2,000 basic words of English enables students to understand 95 percent of academic texts in English. Many of the words on the list, however, are not unique to academic settings, making the textbooks practical vocabulary and self-study guides.

The Mastery textbooks familiarize students with American culture: students read about prominent Americans involved in a variety of fields and businesses. The target vocabulary is introduced in the readings, which are taken from current biographies and have been selected to stimulate student interest.

More Mastery introduces students to Billie Jean King, Nien Cheng, Jon Krakauer, Katharine Graham, Maria Martinez, Madeleine Albright, Ansel Adams, Thurgood Marshall, and Frank Lloyd Wright. The vocabulary in More Mastery is more advanced than the vocabulary in Mastery.