Kamehameha Schools (Honolulu, Hawaii), a privately funded program with approximately 2,000 students and 175 teachers grades 7-12, is implementing a school-wide curriculum evaluation program. As part of this program, the departments of mathematics, science, social studies, counseling, human relations, speech and English collaborated in the development and administration of a Critical Thinking Skills Performance Assessment. The assessment was designed to check the ability of 12th graders to: understand information related to a serious social issue, decide on a plan of action to solve some aspect of the problem, and organize the information and their plan of action into a logical case to gain the support of community "decision-makers." The assessment was administered to a sample of 90 male and female students of low, moderate and high ability. Two sessions totalling 4.5 hours were allowed for administration. Student "cases" were evaluated by four to five teachers using a structured rating sheet. Results indicate that the majority of students have not mastered critical thinking criteria set by our teachers. Plans are being made for staff and curriculum development leading to more explicit instruction in thinking skills, common criteria for evaluation of student skills across departments and on-going assessment at the school level. (Author)