Career preference formation is a vital process for individuals living in a modern society such as Australia. Unfortunately, some young people experience greater difficulty in determining their career path than others, which can have negative consequences for their emotional, financial and even physical wellbeing. In addition, prolonged career uncertainty can lead to long-term unemployment, which has a negative effect on the economy. As current solutions seem to have insufficient effects on the problem of some young people's career uncertainty, this doctoral study draws on modern political philosophy to guide an empirical investigation of the career choice 'capability' of youth. The study proposes a conceptual framework, which draws on Amartya Sen's theory of human capability, to examine factors associated with the development of career choice capability. The proposed framework of this study advocates examining the personal and educational resources to date available to students in order to extrapolate the ability of young people to convert those resources into the freedom to achieve desirable careers. The research was conducted with secondary school students in Years 9 to 12 from a range of government and non-government schools in New South Wales, Australia. The study adopted a sequential phase mixed-methods approach, involving five focus groups (n = 23), followed by a large-scale cross-sectional survey (n = 706) investigating the associations between student characteristics, educational experiences and career (un)certainty. Findings reveal that both personal backgrounds and educational experiences are crucial to students' self-perceived career determination capability. Among the personal characteristics, factors such as language background, parental occupation, self-perceptions, and attitudes to school were significant predictors of career (un)certainty. In terms of school based experiences,career uncertain students were more likely to be from non-metropolitan and non-selective schools, tended to report a lack of access to both career education and elective subjects relevant to their needs, indicated less enjoyment from school in general, and in some academic subject areas. Career uncertain students did, however, report liking Sport/PDHPE (Personal Development, Health and Physical Education) to a greater extent than their career certain peers. Provision of online career guidance made no difference in career certainty for the majority of participants, as most were unaware of listed web resources. The thesis concludes with a series of recommendations, including the development of stronger relationships between students, families, schools and local communities in order to facilitate communication flow in relation to student needs and labour demands, and creating strategies for enhancing career opportunities of young people. Another important recommendation derived from the findings of this study is the provision of career education and guidance to students in late primary or early secondary school, prior to their selection of elective subject choices. The thesis also advocates for improved curriculum diversity at a high school level, and clearer indication of the connections between subjects and career pathways.