This individualized inservice packet on the assessment of student groups is intended to assist the individual teacher and the total staff to analyze the reading competencies of students in order to differentiate instruction and utilize appropriate reading materials. It is one of a nine-part series of booklets--Teaching Teen Reading--in self-instructional format intended as a practical resource for teachers desiring condensed, readily usable answers to questions regarding reading instruction. The booklet's three sections: (1) deal with levels of assessment, sources of data, and student performance; (2) aim to enable teachers to analyze student performance through organizing given test data for a group of students; and (3) give a suggested application. A self-corrective post test, a glossary, and a 38-item bibliography are attached. (SR)