Reliance on teacher assistants (TAs) in mainstream schools to support students with disability and learning difficulties is an increasing trend in Australia. In 2011, over 80,000 TAs were employed costing approximately $3billion per annum [DEEWR. 2012. Job Outlook. Accessed June 2013. http://joboutlook.gov.au/default.aspx]. This paper reports on the employment procedures and practices that affect TAs working in four mainstream schools in Australia. Using data gathered from a qualitative case study conducted over three years, the study found that TAs and teachers have minimal understanding of the TA role. In addition, TAs have limited understanding of employer expectations, education department system policies, the TA career structure and school policies. Existing procedures and practices, both at the education department system level and at the individual school level, exclude TAs from accessing information afforded to other school staff. As a result, TAs work alone and often fail to provide effective support to both students and teachers. It is recommended that school leaders improve employment conditions for TAs at both system and school levels to ensure that students and teachers receive maximum benefit from employing TAs.