This study investigates the assessment methods used in Irish immersion schools to identify students for additional teaching support. An overview is provided of the percentage of students receiving additional teaching support in this context and whether there is a higher rate of students accessing additional teaching support in Irish immersion schools than English-medium schools. The challenges of assessment through Irish as a second language are evaluated. In addition, this study investigates the language used by educational professionals when assessing and/or providing interventions for these students. A quantitative research approach was adopted for this investigation, with a random stratified sample of 20% (N = 29) of Irish immersion schools in the Republic of Ireland completing an online questionnaire. SPSS was used to analyse the data. The findings of the present research contribute to the limited body of knowledge available on the types of assessment used in immersion education to identify students for additional teaching support. These findings are significant as there has been limited research undertaken on this aspect in immersion education and the findings of this study may have implications for immersion education contexts in other countries.