This paper (1) identifies strategies for assessing student instructional needs so that educational prescriptions can be developed to promote learning; and (2) relates the identification of student needs to the development of learning prescriptions. The population discussed includes high school and college students who because of social, economic, political, or educational reasons have not had adequate opportunity to master the basic skills in mathematics and reading. Student needs may be assessed using informal strategies such as interviews, anecdotal information, and grades. Formal methods include specialized surveys, student questionnaires, and tests. Norm-referenced achievement or aptitude tests are economical, effective methods of assessment, when they are valid and based on relevant objectives. However, they may not be valid and reliable for a special, minority sample. Criterion-referenced and mastery tests are useful when their content is similar to the subject objectives. Diagnostic tests may have low reliability and high intercorrelations among subtests, but may be useful in assessing learning disabilities. Information from these tests can be incorporated into a diagnostic or prescriptive learning program based on students' knowledge, capacity to learn, and weaknesses. This process is described, as are some effective prescriptive instructional programs. (GDC)