Despite the documented accuracy of using Functional Analysis (FA) to design effective interventions, it is not being utilised in school settings for students with challenging and highly disruptive behaviours (Shumate & Wills, 2010). This may be due to the time constraints and complexities associated with standard FA procedures, making them difficult to complete in classrooms and requiring specialised staff. Many variations to the standard FA have been adapted to address these issues, including Trial-Based Functional Analysis (i.e., TBFA). The method uses short (1-4 min) assessment probes within typical classroom instruction to measure occurrences of behaviour under different conditions (e.g. Attention, Demand, Tangible and Ignore). Research on TBFA has shown its reliability to identify functions (Bloom et al., 2011), making it a viable option for classroom settings. Furthermore, research on TBFA methodology has been able to show behavioural skills training methods can upskill teachers to carry out TBFA and Function Based Interventions (FBI) procedures with high fidelity, particularly with students who present with disabilities (Flynn & Ya-Yu Lo., 2016). There are, however, some areas requiring further research including generalisation of procedures to new students and using social validity measures to understand teacher’s perceptions and acceptance of the procedures. There is also limited use of procedures with students who are typically developing but engage in highly disruptive or challenging behaviours in mainstream classrooms. This study aimed to expand current research and address the limitations by analysing teacher implemented TBFA and FBI procedures on disruptive or challenging behaviours with typical developing students in mainstream classrooms. Two teachers participated in behavioural skills training on TBFA and FBI methodology and implemented the procedures across three typical developing students who presented with off-task disruptive behaviours. The results showed teachers had the ability to carry out the TBFA and FBI procedures with high level of integrity. In addition, one of the teachers could implement procedures with a high level of fidelity during generalisation measures. Results showed a reduction in disruptive off-task behaviour across all students, indicating the FBI’s were effective in addressing function. Finally, social validity measures indicated teachers found the procedures easy to implement and felt they had a positive impact on student behaviours.