The Department of Education has contracted AIR to evaluate the impact of the use of a literacy-focused workbook in English as a Second Language (ESL) instruction on adult learners. Using a randomized design, AIR has assigned approximately 1,800 low-literate adult ESL students from 10 programs to an intervention condition, where teachers use the workbook-based literacy instruction, or to a control condition, where classes are taught as usual. AIR has assessed students after approximately 15 weeks (minimum of 60 hours of instruction) on reading, writing, speaking, and listening to evaluate the impact of the intervention. The study will produce a fully evaluated curriculum and materials reflecting the principles of literacy instruction for adult ESL learners. A final report will describe the study and present the findings, evaluating the impact of explicit literacy instruction on low-literate ESL learners.