As recently as the year 2004, the category of ‘temporary’ teacher effectively did not exist in the NSW public education employment landscape. Between 2004 and 2015 – years for which reported data are available on the numbers of both casual and temporary staff in schools – casual employees have remained at a steady proportion of approximately 10% of all employees. The proportion of temporary staff has, however, increased steadily, from approximately 5% in 2004, to 15% in 2015. While the current temporary category was initially established to provide an intermediate level of employment security between permanent and casual, it would appear that it has instead led to greater levels of precarity within the teacher workforce overall. We suggest that this dynamic constitutes a new mode of casualisation, as temporary teachers undertake employment ‘blocks’ of between one month and one year, without the security and other benefits which come from being a permanent employee. This presentation draws on data out of a very large, recent, state-wide survey of 18 234 members of the NSW Teachers’ Federation in order to explore the nature of this relatively new, and growing, category of employment for teachers. We find that temporary teachers report significant pressures, including the stress and difficulty of finding a permanent job and a perception that hiring and promotion processes are both unclear and unfair, with impacts for the integrity of industrial democracy. We discuss such issues within the context of the current climate of devolution over staffing, where temporary staff can be preferred because they are often already known to the school, whereas permanent teachers transfers are not. Temporary teachers are also easier to remove. The plight of temporary staff members is not new to either the teachers’ union or the NSW Department of Education; this was evident in the union’s (partially) successful attempt to transition thousands of temporary staff into permanent positions in late 2017. At this potentially crucial moment in the industrial landscape for teachers, we contribute to the debate by providing new data on the experience of temporary teachers, subject as they are, we argue, to a new form of casualisation.