Critical thinking in today's education is one of the primary goals of educational programs around the world. As a desired outcome, critical thinking allows students to be effective learners in the learning process, responsible citizens in their daily life and successful employees in the job market. Therefore, students need to be socialized to carry out research, make decisions and solve problems in the high school context before moving to university. Therefore, this book aims at intorducing a brief critical review about critical thinking and then analyzing two second year baccalaureate textbooks of English, namely Insights into English and Ticket to English to find out if they help high school students develop a degree of critical thinking.