Teaching in Australian universities is performed by two groups of academic staff, defined by the nature of the employment contract. While permanent academic staff are engaged in teaching and research, a growing group of hourly paid or casual employees deliver teaching services. This article explores some key dimensions of the work and aspirations of these casual academic staff, including levels of access to job and career supports, and career and job satisfaction. The 2011 Work and Careers in Australian Universities survey of staff in 19 universities provides data from more than 3000 casual academic staff. Three related issues are investigated: the characteristics of labour supply in the casual academic labour force; the key defining boundaries of labour segmentation; and barriers between casual and permanent academic employment. A typology of casual academic staff is proposed. In particular, gender, type of university and discipline are investigated to examine whether these have an impact on the various measures of career opportunity, job satisfaction and the incidence of the 'frustrated academic'. The research reveals that the casual academic labour market is not integrated with the permanent academic labour market and that discipline is a key determinant of the level of 'frustration' of casual academic staff.