As part of a cross-national research project on literature instruction in middle-grade classrooms in Great Britain and the United States this study explored the effects of external assessment on that instruction. The focus was on the literature selected, the class time allotted, and provisions made for students' choices. The study explored the teaching of four language arts teachers in a middle school and junior high school in the south central United States and two secondary schools in the southwest of England. The English classes had 28 and 31 students respectively, and the U.S. classes each had 27 students. Data sources included observations of instruction, weekly interviews with teachers and students, interviews with auxiliary personnel, examination of official policy documents, and personal reflections of the researcher in journal form. In the United Kingdom, the National Curriculum provides for the teaching of a standard curriculum, and a national assessment, the Standard Assessment Tasks, is taken by students at key educational stages. Assessment on a national scale is not a feature of American schools, but both study schools were in Texas, where students take the Texas Assessment of Academic Skills as part of the state testing program. In England, the National Curriculum had a strong influence on teachers' practice, and the external assessment both drove much of the curriculum and worked against student choice in reading selections. External assessment had little effect on the choice of literature studied in the Texas schools, and student choice was considered by one teacher and not the other. Results suggest that external assessment has an impact on instruction, and that the higher the stakes, or more distant the level of assessment, the greater the influence. External assessment does not appear to coexist comfortably with student choice of literature. (Contains 1 figure and 14 references.) (SLD)