This study assessed patterns of instructional leadership sources. The instrument, Sources of Instructional Leadership (SOIL), was based on instructional leadership and effective schools literature. It dealt with the management of instructional resources, and related to one of six leadership functions: organizing, coordinating, developing, supporting, and monitoring instructional resources; and fostering an academic climate. The respondents, professional educators, included 307 out of 436 possible test trial subjects from seven test trial schools. Their responses were combined with 129 out of a possible 151 responses from three pilot schools and analyzed for response pattern using discriminant analysis. The SOIL questionnaire consisted of 31 instructional leadership items for each of five roles (principal, vice principal, department head, specialist, and teacher). SOIL proved to be a valid and reliable instrument and indicated that patterns of instructional leadership were complex and diverse, but perceptible to the individuals in each school. The results suggest that schools have instructional leadership teams that are identifiable and alterable and that instructional leadership systems can be identified by describing the interrelationships among roles and functions rather than focusing on the leadership of individuals. (JAM)