Selected findings are presented from a study of classroom teachers' testing needs, testing proficiencies, testing practices, and testing resources in the public schools in Ohio. Focus was on determining how principals and supervisors can assist: (1) teachers in identifying and alleviating the most common test construction errors found on teacher-made tests; and (2) Ohio schools in providing resources to better support teachers' testing responsibilities. A sample of 586 school supervisors and principals and 326 classroom teachers completed administrators' and teachers' versions, respectively, of an assessment of needs instrument for 45 identified competencies and of perceived proficiencies in those competencies. Administrators and teachers also rated the availability of resources for testing and guidelines. Teachers further described their testing practices and provided a total of 175 samples of teacher-made tests. Teachers scheduled teacher-made tests frequently and used a variety of item types in making the tests; most teachers constructed their own items. Competency needs for testing were rated higher than beginning teachers' testing proficiencies by administrators. Teacher proficiency was rated highest by teachers and lowest by supervisors, with principals in the middle. Administrators and principals generally agreed on proficiency needs. Available resources appeared inadequate to support testing responsibilities. Teacher-made tests contained errors in format or construction. Guidelines and item type error formats for identifying and alleviating test construction errors are presented, with test examples. Seven tables present study data. (SLD)