Critical thinking ability is a difficult concept to define. It involves reasoning and active consideration of what is received rather than a forthright acceptance of the ideas. It has been argued that when the focus of testing is the examination itself, the critical thinking ability of the learners cannot be boosted. However, different types and formats of tests can engage the learners in an active critical thinking when they are appropriately prepared. In this paper some of these tests used in the literature and the way they engage the learners in critical thinking activities are explained. The paper concludes that different tests of language can be manipulated so that they can engage the learners in critical thinking activities. Implications for teachers and test developers are also provided.