Since 9/11, colleges and universities throughout the nation have developed and implemented new courses and degree programs in homeland security and emergency management. A valued learning outcome of these programs, like most university studies in general, is to develop critical thinking skills in students. However, this can be a challenge because the nature of critical thinking and approaches to teaching and assessing it in higher education are debatable. This paper provides a brief overview of the literature on critical thinking, and looks at the importance of developing these skills in students of homeland security programs so that they are able to adapt successfully in a rapidly changing environment. Finally, this paper discusses two teaching strategies, guided class discussions and case studies, to develop critical thinking that have been used by the teacher in undergraduate and gradate level courses in homeland security.