This guide presents ways for practitioners to use Chapter 1 achievement data to better understand and evaluate elements of a Chapter 1 program. A variety of types and levels of questions can be addressed with achievement data. Combining standardized achievement test scores with data from the program and from the regular classroom greatly increases the range of questions that can be answered. Full group data allow evaluation of: (1) how program results compare to district, state, or national results in each subject area; (2) what the long-term effects of the Chapter 1 program are; (3) how the standardized test results compare to performance on program criterion measures; and (4) what the trends in achievement over time for each cohort are. Subgroup data allow the determination of the relative gains for students at different levels, and assessment of how students who exit the program compare with those who remain. Individual data can provide insights into how to deal with students who do not seem to progress. Case study analysis can reveal much about the achievement of individuals. Data are generally collected with a specific purpose, but this guide shows ways in which additional questions and hypotheses can be examined. Five graphs and three tables present the study results. (SLD)