This study sought to investigate what pre-service and in-service trained teachers understand byÂ differentiated instruction, and the extent to which they practised differentiating instruction in their classrooms. Three hundred and seventy-nine participants were randomly drawn from selected primary and secondary schools situated in the north-eastern, central, southern, and western parts of Trinidad. Findings of the study revealed that 58 percent of the respondents understood the concept of differentiated instruction. However, the majority of teachers did not differentiate content and product in their classrooms. While responses from participants in the questionnnaire survey indicated that teachers generally understand and engage in process differentiation, responses from focus group interviews suggested that this type of differentiation is not a planned and conscious strategy. The study also highlighted various challenges related to implementation of differentiated instruction. These include the lack of time for planning adequate teaching, limited space for group work, and lack of administrative support.