This study investigates how mathematics secondary schools' teachers in Jordan perceive critical thinking and compares teachers' perceptions before and after educational reform. Data were collected from 12 schools twice: in 1988 and in 2004 by interviewing 47 Mathematics teachers. The interview included questions related to teachers' understanding of critical thinking, its role and importance in learning Mathematics, and instructional strategies that could help improve students' critical thinking skills. Results found no improvement in secondary Mathematics teachers' perceptions of critical thinking despite 15 years of educational reform. The majority of Mathematics teachers seemed not to have a clear and adequate understanding of critical thinking. Though most of the teachers claimed they have to teach critical thinking, more than half of them could not suggest any learning situation that could help in fostering critical thinking in Mathematics classes. Also most of the teachers claimed that critical thinking would help students in learning Mathematics; yet less than half were able to give a convincing justification for that. A small percentage of the secondary Mathematics teachers believed they can help all students to foster their critical thinking. It is thus recommended that the concept of critical thinking be transferred from the realm of rhetoric to the field of practice. The paper ends with some recommendations related to the Mathematics teachers training programs in view of the results of this study.