The focus of the thesis is an exploration into students’ vocational knowledge in the context of Dutch vocational education and training (VET). The reason students’ vocational knowledge requires exploration is because there is no consensus among scholars in the field of VET about how to theorise the nature of students’ vocational knowledge; most (not all) scholars rely on dichotomous conceptualisations, such as theory versus practice, general versus specific or explicit versus implicit. However, such commonly used dichotomies are not very helpful to understand the complex nature of vocational knowledge. Vocational knowledge is more than putting bits of theoretical and practical knowledge together, it is characterised by sometimes-intimate relationships between knowledge and actions. As a result of the above-mentioned gap in the VET literature, there is little empirical research on how VET students develop vocational knowledge and the extent to which this is occupation-specific knowledge. To understand students’ vocational knowledge, four different aims are formulated and carried out in four studies. The aim of the first study is to identify powerful vocational learning environments to enable the selection of a case that represents high quality vocational learning and teaching. With an eye on analysing students’ vocational knowledge, the second study aims to conceptualise the nature of vocational knowledge that avoids dichotomies. Therefore, two conceptual frameworks are integrated; the idea of contextualising is introduced which is based on cultural-historical theory to highlight the crucial role activity plays in knowledge development and to understand the relationships between the mind (i.e., what people think (and feel)), and action (i.e., what people do). Secondly, the theory is supplemented with ideas from inferentialism, a philosophical semantic theory of meaning to provide a useful way to focus on students’ processes of knowing and to reveal students’ vocational knowledge in terms of ongoing reasoning processes. The third study uses the conceptualisation of vocational knowledge to explore how students develop vocational knowledge in occupational practice, and to illustrate the process of contextualising. The forth study aims to describe what characterises students’ vocational knowledge using an analytic framework that distinguishes between occupation-specific knowledge components and qualities. This thesis contributes to research scholarship in the field of VET and an understanding of students’ vocational knowledge in practice. The theoretical framework of contextualising supplemented with inferentialism provides an alternative way to focus on students’ processes of knowing and helps to reveal students’ vocational knowledge in terms of reasoning processes. The empirical explorations and illustrations of students’ vocational knowledge contribute to the scholarly literature and practice on understanding the nature of vocational knowledge, how students develop vocational knowledge and what characterises their vocational knowledge. The intention to introduce the idea of contextualising is not about reinventing the wheel but rather an attempt to understand how it turns and how it functions. The intention of this thesis is to encourage dialogue and move the debate about the nature of vocational knowledge further, and hence, to provide some “food for thought”.