As the nation gears up for a massive educational restructuring, a major issue regarding thousands of teachers who function at substandard levels has yet to be addressed, and even the latest educational restructuring proposals show little concern for this problem. Indicators of marginality include failure to maintain discipline, difficulties in conveying subject matter, poor relations with students, or inability to achieve desired outcomes. However, the performance of marginal teachers can be improved with adequate diagnosis and appropriate rehabilitative strategies, since marginal teachers, unlike those who are incompetent, are capable of reasonable performance. Earlier research estimates that between 5 and 20 percent of teachers are marginal. Most previous studies separate the roots of marginality into either professional or personal deficiencies. For the present study, a questionnaire was distributed to 518 elementary and secondary schools in California to determine administrators' perceptions of the scale, causes, and difficulties of marginal teachers and to identify appropriate response strategies; of this total, 131 completed surveys were returned, for a response rate of 26 percent. According to the responses received, the major perceived causes of marginal teaching included the inability to control classrooms, lack of motivation, burnout, and personal crises. There was general agreement that marginal teachers are uniquely vexing administrative problems. Many administrators were unable to differentiate marginal from incompetent teachers and endorsed simple remedies such as dismissal or reassignment. A variety of personalized intervention strategies were suggested, of which peer coaching and continuous classroom observation were considered to be the two most effective for improving the performance of the use of marginal teachers. (Contains 24 references.) (TEJ)