This study examined the roles, functions, and effectiveness of a group of teachers who became Instructional Leaders (ILs), assuming major responsibility for assuring the implementation of a voluntary school improvement program within their respective schools. The program, called SITIP (School Improvement Through Instructional Process), and initiated by the Maryland State Department of Education, supported local education agencies in their adoption and implementation of four research-based instructional models: Active Teaching; Mastery Learning; Student Team Learning; and Teaching Variables. Data were collected for the IL study from local educators, students, and state technical assistants in the form of observational interviews, questionnaires, and document analysis. Factors or conditions related to the success of teachers as ILs are summarized in the form of recommendations. For a teacher to be successful as an IL: (1) implementation in the first year should be limited to the teacher's school; (2) ILs should be given sufficient time to plan and develop enough materials for a complete course before implementation begins; (3) the IL should be involved from the initial phases of planning and training; (4) IL expertise in the instructional model is necessary; (5) IL leadership style should be democratic; (6) the two key tasks of the IL are training and coaching other teachers in the innovation; and (7) administrative support is essential for IL success. (JD)