Differentiation concerns teachers’ strategies and methods to design teaching in response to the natural variation in heterogeneous classrooms. In this study, it is looked upon as a method of inclusion in English teaching to enhance the students’ learning regardless of their levels. The present study aims at exploring teachers’ experiences of working with differentiation in the English upper secondary classroom, in order to discuss strategies that are used, challenges that are faced, and outcomes that are noticed when applying differentiation. Six teachers of English in different schools were interviewed to obtain their experiences. The data was collected via semi-structured interviews and the participant’s answers were analysed and categorised into various themes. Although the results revealed that the participants utilized differentiated teaching to meet the students' different learning styles and interests, all participants described teaching English in heterogeneous classrooms as a challenge. They referred to the outcomes of applying differentiation and how it can have an impact on students’ individualized learning. According to all the participants in this pilot study, the most effective solution to manage heterogeneous classrooms is applying differentiation. Nevertheless, they all agreed that there is no simple way of applying it and teachers can choose different contents and methods for teaching English to help students reach their learning objectives.