Test anxiety is one of the most confronting issues in modern times with the increase in the number of standardised and high-stakes testing. Research has established that there is a direct link between test anxiety and cognitive deficits. The aim of this study is to determine the test anxiety scores of the students with intellectual disabilities in South Australia. It also provided insights into the reasons for high-test anxiety in the participants under study. The Spielberger's Test Anxiety Questionnaire was administered on students with intellectual disabilities in stage 1. Interviews were conducted with participants with intellectual disabilities, parents and teachers in stage 2. Questionnaire findings revealed that the majority of the adolescent females and males and all adult females with intellectual disabilities had high test anxiety scores. However, the majority of adult males with intellectual disabilities obtained moderate test anxiety scores. In the worry and emotionality subscales, it was also found that the majority of adolescents and adults with intellectual disabilities were found to score high. The high test anxiety scores have been justified by the interview responses obtained from the three groups of respondents. A number of factors have been identified to be the major predictors of test anxiety in students with intellectual disabilities.