To help improve research-based knowledge of effective instruction for low-literate ESL (English as a second language) learners, the National Center for Education Evaluation and Regional Assistance of ED's (U.S. Department of Education's) Institute of Education Sciences contracted with the American Institutes of Research (AIR) to conduct a Study of the Impact of a Reading Intervention for Low-Literate Adult ESL Learners. The intervention studied was the basal reader "Sam and Pat, Volume I," published by Thomson-Heinle (2006). "Sam and Pat" was selected as the focus of the study because it offers an approach to literacy development that is systematic, direct, sequential, and multi-sensory. The study produced the following key results: (1) More reading instruction was observed in "Sam and Pat" classes, while more English language instruction was observed in control classes; (2) Although students made gains in reading and English language skills, no differences in reading and English language outcomes were found between students in the "Sam and Pat" group and students in the control group; and (3) There were no impacts of "Sam and Pat" on reading and English language outcomes for five of six subgroups examined. Appendices include: (1) Assessment Selection, Administration, and Scoring; (2) Supplemental Tables and Figures for Chapter 2; (3) Classroom Observation Methods and Instrument; (4) Power Calculations and Impact Estimation Methods; (5) Supplemental Tables for Chapter 3; and (6) Supplemental Tables for Chapter 4. (Contains 44 tables, 12 figures, and 33 footnotes.) [For the executive summary, see ED514093.]