The limits of my language are the limits of my mind. All I know is what I have words for. —Ludwig Wittgenstein The Importance of Vocabulary

There is a clear consensus among literacy researchers that accelerating vocabulary growth is a vital and often neglected component of a comprehensive reading program (Baumann & Kame’enui, 2004; NICHD Report of the National Reading Panel, 2000). Numerous studies have documented the strong and reciprocal relationship between vocabulary knowledge and reading comprehension (Stahl & Fairbanks, 1987; Beck et al., 2002; Graves, 2000; Baker et al., 1995) as well as general reading ability (Stanovich et al., 1998). Research focused on school-age second language learners similarly concludes that vocabulary knowledge is the single best predictor of their academic achievement across subject matter domains (Saville-Troike, 1984). Striking lack of vocabulary instruction Given the pivotal role of vocabulary in virtually all aspects of academic competence, it is alarming that classroom research consistently reveals how relatively little focused academic vocabulary instruction actually occurs in the typical K–12 classroom. For example, Durkin (1979) found that upper-elementary teachers spent less than 1 % of their overall reading instruction focused on vocabulary. More recently, Scott and Nag