Although research provides ample evidence of teaching methods that facilitate students' learning of specific word meanings, the potential of instruction to impact students' general vocabulary knowledge has remained an unanswered question. This article reports on a three-year formative experiment that developed, implemented, and tested a long-term,…

This study evaluated the efficacy of the Word Learning Strategies (WLS) supplementary program designed to develop upper-elementary students' vocabulary skills in order to improve reading comprehension. The study used a true, group-randomized, experimental design, which randomly assigned 46 4th grade classrooms (n=1324 students) from 12 districts…

This study evaluated the efficacy of the Word Learning Strategies (WLS) supplementary program to improve elementary students' vocabulary skills and reading comprehension. The study used a multi-site cluster randomized, experimental design, which randomly assigned 92 4th grade classrooms (n=2558 students) from two cohorts to a treatment or control…