These three case studies highlight the implementation and impact of Mid South Middle Start by: (1) contributing toward an in-depth understanding of what it means to be a school implementing Middle Start; (2) describing a holistic portrait of the schools' participation in Mid South Middle Start; and (3) assisting the Academy for Educational Development (AED) in giving formative feedback to the Foundation for the Middle South (FMS). Three schools were selected as case-study subjects based on: (1) location of the school (seeking even distribution among the Mid South states of Arkansas, Louisiana and Mississippi); (2) type of grantee school; (3) types of reforms planned; (4) school history in terms of academic performance and stability of administrator and faculty turnover; and (5) the school's availability and willingness to be studied in detail. The studies of Appleton, Jeyson, and Mt. Olive Middle Schools are based on two years of qualitative data collection by a team of AED researchers. The research team examined: (1) the context of implementation of Middle Start; (2) the role of Middle Start in school improvement efforts; (3) the accomplishments and challenges that the school encountered; and (4) the impact of Middle Start in promoting academic achievement, developmental responsiveness and equity in the school. In addition to gathering data specifically for these questions, the case-study research also included more general inquires into each school's background, physical setting, and historical context. Research included one-day site visits in both the fall and spring of each of the case-study years, as well as other site visits and interviews with the Middle Start director of school improvement services. During the site visits, the research team conducted interviews with the following school staff: (1) principal and/or assistant principal; (2) teachers, particularly members of school leadership and grade-level teams; (3) counselors and librarians; and (4) Mid South Middle Start coaches. Generally, classroom instruction was found to improve with implementation of Middle Start, with many teachers in the three schools using a variety of innovative and developmentally appropriate teaching practices. School climate also improved: schools became more student-centered by increasing support for students and celebrating their work. Buy-in among teachers, teaming, and distributed leadership were evident in the three schools and were main drivers of change. Staff in Middle Start schools described Middle Start as providing a "shared vision" and an "alternative way of thinking," and credited the initiative with improving staff understanding of middle-level concepts and the needs of young adolescents, fostering communication among school staff, increasing family involvement, and helping the school maintain a focus on the improvement of teaching and learning despite numerous challenges and limited resources. (Contains 8 footnotes.)