The study was undertaken to evaluate the classroom assessment employed by the teachers, the critical-thinking and academic performance of the students in the laboratory high schools (LHS) of Central Bicol State University of Agriculture, school year 2012-2013. The descriptive-evaluative, descriptive-correlation and descriptive-comparative methods of research were used. The findings revealed that only 11 out of 50 types of classroom assessment techniques are being used in the two laboratory high schools of CBSUA, namely: CDELHS and CDE–CSHB. Except for the use of human tableau or class modeling and application cards in few instances, the other techniques used by the teachers were classified as low-order thinking skills like “remembering” and “understanding”. “Applying”, “analyzing”, “evaluating” and “creating” were rarely used by the teachers. There were significant differences in the levels of critical thinking among the second year students in the two LHS along remembering, understanding, analyzing and evaluating while for third year high school students in the two LHS there was significant difference in evaluating but not significantly different with the rest of the levels. In terms of students’ academic performance in Science and “remembering”; English and “evaluating” in school A, there was a significant relationship between the level of critical thinking among students and their academic performance in the three subjects. The teacher-related factors along gender, marital status, employment status, and number of awards received, were significantly associated with the questioning skills of the teachers. In general, the findings indicated that there were significant association between the student-related factors and the different levels of critical thinking.