This is one of a series of reports based on an ongoing reality test of systemic evaluation for instructional decision making. This feasibility study is being carried out by the Center for the Study of Evaluation with the Laboratory in School and Community Relations at a suburban Los Angeles high school (called Site A). Viewing a school as a cultural/ecological system, systemic evaluation is a set of principles to guide local development of processes to gather, organize, and utilize information relevant to the needs and values of the system and its members. This paper examines methodological issues derived from a multilevel analytic perspective on local school improvement. A multilevel analytic methodology examines data from the different levels (student, classroom/teacher, school, district) of the educational system and their interconnections. It employs test analysis procedures that reflect instructionally sensitive performance variation. It links the conceptualization of an educational process to its measurement and analysis at various levels. It uses analytical procedures that potentially identify effects at and within each level of the educational system. Numerous tables and a three-page list of references conclude the paper.