Critical thinking is an essential life skill required by most people in today's complex world. Development of critical thinking is important in preparing students for post-secondary education and for competing economically in the global environment. A number of studies in developed countries have advanced some strategies for fostering critical thinking, however, few studies have been conducted in Sub-Saharan Africa. In Kenya, where this study was conducted, development of critical thinking is one of the objectives of teaching English in secondary schools. The purpose of this study was to explore how teachers of English in a secondary school foster critical thinking in their classes. The findings of the study revealed that while teachers acknowledge the importance of critical thinking in learning, they do not have a clear understanding of what it is.They were also aware of the suggested pedagogical practices for fostering critical thinking but these theoretical perspectives did not reflect in their teaching, as some of the practices were not fully explored.Teachers face challenges such as superficial understanding of critical thinking, time constraints among others.