The Ohio Vocational Achievement Tests are specially designed instruments for use by teachers, supervisors, and administrators to evaluate and diagnose vocational achievement for improving instruction in secondary vocational programs at the 11th and 12th grade levels. This guide explains the Ohio Vocational Achievement Tests and how they are used. The guide is divided into four sections. The first section explains the nature and purpose of the tests, including test development, what the battery measures, administration, organization of the tests, and sample test items. The second section covers statistical data concerning the tests including reliability and the standard error of measurement. In the third section, uses of the test battery are explained. Benefits mentioned are the improvement of instruction, school and community research, and student benefits. In the last section, information on using the test results is provided. Appendixes to the guide contain sample forms and results of the tests. (KC)