This study examined the effect of complexity of problems on the degree of disparity between intuitive (PDM) and computer-assisted (DSS) decision-making. 840 teachers chose intuitive solutions for educational dilemmas, and recorded the relative importance of the guiding criteria. Utilizing this information, DSS calculated preferred solutions. Of the 2 measures of complexity, the number of alternatives contributed more significantly than did the number of criteria to explanation of the variance between PDM and DSS. This finding casts light on cognitive processes activated during complex decision-making and clarifies the conditions under which the use of DSS in schools is advisable.