An open social systems model is used to frame and test a series of hypotheses. The socioeconomic status of the environment and four internal system elements (structure, individual, culture, politics) of the school are used to explain two sets of school outcomes: student achievement and teachers' assessments of overall school effectiveness. A typical sample of 145 elementary schools in Ohio is used to test the relationships. The model and results are useful in understanding how this set of key variables as a whole defines quality elementary schools. (Contains 5 tables and 1 figure.)