As teacher educators, preparing student-teachers who are able to address diverse student needs is our main concern. It has been suggested in the literature that teachers who are adaptive to students' needs are those who possess adequate pedagogical content knowledge or pedagogical understanding. However, it is not uncommon for teacher educators to find student-teachers with diverse pedagogical understandings even at the point of graduation from the teacher education programme. This paper aims to explain and analyse the development of pedagogical understanding among student--teachers in an initial teacher education programme. The findings are drawn from a study conducted at the Hong Kong Institute of Education where in-depth interviews were carried out during the four-year programme. The findings from the three selected cases provide an explanation for why some individual student-teachers show continuous development, whereas others remain confused in their pedagogical understanding throughout the teacher education programme. While acknowledging individual differences in pedagogical understanding, we attempt to explain such differences by investigating the relationship between different dimensions of the student-teachers' learning such as the integration of pedagogical understanding with the teaching contexts, integration of feedback from lecturers and supporting teachers, and their focus of concern. The findings reveal that the three cases demonstrate different levels of pedagogical understanding and possess varying "senses of agency". Of the three cases, the first one, Peggy has the strongest sense of agency. Despite influences related to classroom management, diverse learning ability among pupils, and the teaching methods which pupils were accustomed to previously, she actively introduced rhythmic movements into her lessons, developed pupils' ability to learn gradually and achieved an impact on pupils' learning which was also recognized by her supporting teacher. The analysis suggests that the second case, Lilian has a weaker sense of agency as she was severely limited by influences in the teaching context in her first teaching practice and resorted to teacher-centered teaching strategies. She improved later on in the programme and started to plan her own learning, drawing on the feedback she received as well as learning from other taught modules, from feedback from various sources, and from her pupils' responses to her teaching and her own evaluation of her teaching. The third case, Stephanie remained confused throughout the programme and struggled with the implementation of student-centered teaching strategies. The ability to practice one's own convictions and demonstrate an active sense of agency distinguishes the student-teacher who achieves better pedagogical understanding. Drawing on the findings, the paper concludes that it is crucial for teacher educators to identify ways to nurture a sense of agency among student-teachers. Implications for teacher education programmes are discussed, including providing opportunities for student-teachers to be able to articulate and integrate their pedagogical understandings, as well as negotiate how to accomplish their learning and teaching targets despite complex classroom situations.