Over the course of their kindergarten through twelfth grade education, children in American public schools will spend the equivalent of one school year under the guidance of a substitute teacher. Yet in most districts, substitutes are given the keys to the classroom without a day's training. While requirements vary by state, some may hold advanced degrees, while others may have earned only a high school diploma or G.E.D. This mixed methods study examines the perceptions of substitute teachers, permanent teachers, and school administrators toward professional development for substitutes. I interviewed five administrators, five substitute teachers, and five classroom teachers. The data I collected from these interviews informed two surveys: one sent to a sample of 176 permanent teachers and the other to the entire population of 151 substitute teachers in the Deerfield School District 1. I then conducted follow-up interviews with five different classroom teachers and five substitute teachers. I found that classroom teachers believed that substitute teachers did not do a good job at classroom management, did not know how to teach the curriculum well, and were not competent with instructional strategies. The data also demonstrated that substitute teachers did not believe they did particularly well in each of these areas, but that they were eager to learn about them. Although a common method used for offering such professional development is a class or workshop, and while this was the most popular method requested by substitute teachers, more than half of all substitute teachers in the study reported they were interested in classroom observations, mentoring, networking, and in attending the same professional development as permanent teachers. The recommendations of this study, based on input from the stakeholders themselves, hold promise for growing substitute teachers into what children need in the absence of their permanent teacher: an effective classroom instructor. (Contains 4 tables, 2 figures, and 26 footnotes.) [Ed.D. Dissertation, University of California, Los Angeles.]