To investigate teachers' beliefs about critical-thinking (CT) activities for different populations of learners, the Critical Thinking Belief Appraisal (CTBA) was administered to 145 practicing secondary teachers. Teachers rated both high-CT and low-CT activities as more effective for high advantage learners than low advantage ones, demonstrating strong "advantage effects." They also rated high-CT activities as more effective than low-CT ones for both high-advantage and low advantage learners, demonstrating "pedagogical-preference effects" stronger for high-advantage learners than low-advantage ones. Although these results are inconsistent with the assertion that teachers favor low-CT activities over high-CT ones for low-advantage learners, the results suggest that low-advantage learners may receive fewer high-CT activities in schools, which may hinder their academic performance. Studies of the development of teachers' CT-related beliefs are needed, with the goal of establishing teacher-education practices emphasizing appropriate use of high-CT activities for low-advantage learners.