Because organizational effectiveness of schools is difficult to define, a model is needed to explain the complexities of the concept. Two models offer some promise. One is the goal model, which defines effectiveness as the degree to which organizations meet or surpass their goals (either official or operational). The other is the system resource model, which measures effectiveness in terms of the organization's ability to secure advantageous bargaining positions and thereby acquire scarce and valued resources. Criticisms can be made of each model, but integration of the two models can increase their utility. However, four additional factors need to be considered, including the dimension of time, the organizational level under consideration, multiple constituencies (each with different ideas about effectiveness), and multiple criteria of effectiveness. To specify dimensions of effectiveness in the integrated model, Talcott Parsons' four functions of social systems should be added, involving adaptation, goal attainment, integration, and latency, or value system maintenance. For each function, the model includes multiple indicators (or criteria) of effectiveness, and for each indicator, the model adds time, level, and constituency factors. (Author/RW)