An instrument which can be used to measure the school library/media ability of students in grades 4-12 was developed in Ohio, using 2,670 students from rural, suburban, and urban settings. The test covers five broad areas: (1) how things are organized, (2) the skills needed to select appropriate resources, (3) the skills needed to use each resource, (4) the skills needed to comprehend the information given, and (5) the skills needed to present the information in a meaningful way to others. Content validity of the test was established by a table of specifications from about 60 national and state elementary, secondary, and college curriculum guides in library/media skills, and through assessment by a panel of 68 Ohio library professionals. Test items were then analyzed and rewritten according to statistical information obtained in the pilot test and according to comments from the panel of experts. Reliability was assessed both by group differences and by item analysis. The test can be used for diagnosing areas where students need library instruction, as a pre-post test to determine effectiveness of library instruction, and to correlate studies between library/media skills and academic achievement. (BK)