to which the conceptions of school effectiveness in models are consistent or .5 compatible.High model congruence indicates that the criteria and indicators of effectiveness developedfrom the models are similar, consistent, compatible, of at least not conflicting in nature. Onthe other hand, model incongruence represents'^! the potential conflict between conceptionsor indicators of school effectiveness^ developed from different models. To different peoplewho have different concern sj different models may be used to define and measure schooleffectiveness. Ifthct chosen models are congruent, then these models can be integrated andprovide a complete and consistent assesment of school effectiveness from different per ?spectives. If the chosen models are incongruent, then the evaluation of school effectivenessand ways for maximizing school effectiveness may become very? controversial, since thecriteria and indicators of effectiveness developed from tht models may conflict and cannot bemaximized at the same time.

For each case of maximizing or studying school effectiveness, we would like; to knowwhether the models used to conceptualize school effectiveness are congruent: and whetherthe categories of school effectiveness are congruent. If both category'; congruence and modelcongruence can be ensured, then evaluating or maximizing-, school effectiveness would beless problematic. How to ensure these two kinds of congruence when studying schooleffectiveness in different contexts still needs- further exploration.

Assuming that model congruence exists between models, some investigators tried tointegrate several models and proposed multiple criteria models to define and measureeffectiveness (see Cheng, 1986b; 1993h; Hackman, 1987; Hackman and Walton, 1986; Hoyand Miskel, 1991; Miskel, McDonald and Bloom, 1983). For example, from Hackman andWalton's (1986) idea, school effectiveness may be defined h" owing three

dimensions: