First language learners acquire vocabulary in the context of participation in discourse, and the quantity and richness of that discourse is the best predictor of their progress. Similarly, we argue, engagement in discourse, in particular debate and discussion, is an effective component of classroom instruction for second and foreign language learners. Evidence supporting the effectiveness of a particular discussion-based program, Word Generation, is presented, in particular its effectiveness with current and former second language learners of English. Principles implemented in Word Generation that could be applied in any educational setting are identified. [This paper was presented at the 8th International Conference on Practical Linguistics of Japanese at the National Institute for Japanese Language and Linguistics, and was published in "Journal of Japanese Linguistics," v30 p7-14 2014.]