The effectiveness of inquiry-based instruction (IBI) is well documented, however its use with students with mathematics difficulties (MD) has been limited, since it is often thought such methods are unsuitable for low attaining students. However, this belief is not entirely evidence based, and little research has explored how students with MD perceive IBI. In addition, previous research has demonstrated that students’ beliefs can have an impact on mathematics performance. This thesis therefore explores two research questions: (1) How do students with mathematics difficulties perceive inquiry-based instruction? and (2) Are students’ beliefs (e.g. mindset) associated with the effectiveness of inquiry-based instruction for students with mathematics difficulties? In a multiple case study involving two secondary schools from the United Kingdom, students with MD were taught using an inquiry approach to learning mathematics. Data were collected through a combination of questionnaires, lesson observations, student interviews, and pre-test/post-test assessments. Cross-case analysis suggested that students with mathematics difficulties perceived inquiry-based instruction according to four themes: IBI as a form of empowerment, IBI as a form of neglect, importance of the teacher, and importance of peers. The expression of the first two themes seemed to differ depending on the students’ mindsets. In addition, the students’ beliefs (including mindset) were analysed according to McLeod’s (1992) framework of beliefs in mathematics. Beliefs about mathematics, mathematics teaching, the self (including mindset), and the social context appeared to be associated with the effectiveness of IBI. Students with fixed mindsets showed poorer engagement and persistence compared to students with growth mindsets, but surprisingly, this effect was not reflected in test scores. Future research should seek to further explore the contextual factors that contribute to the effectiveness of inquiry instruction for students with MD.