This chapter reports the results of a study that evaluates the effectiveness of a Philosophy in Schools (PIS) programme in developing students’ thinking skills and English competence in Hong Kong. Sixty-two Secondary 3 English as a Second Language (ESL) students and their three Integrated Humanities (IH) teachers participated in this study. With training and support from the researcher, the participating teachers taught the participating students PIS in English during IH lessons. The students were found to be capable of reasoning and arguing in a competent way about philosophical problems arising from various stimuli prepared by their teachers according to the IH curriculum. It was also found that PIS played a major role in promoting the students’ critical and creative thinking, and helped the development of their English language proficiency to a significant extent. In addition, both the students and teachers were found to have a generally positive attitude towards doing philosophy in the classroom. The findings of this study suggest that integrating philosophy into the IH curriculum can promote critical thinking, creative thinking, and English language proficiency in ESL students.