Administrative data sets can play a key role in informing and influencing education provision. To date, longitudinal analysis of special educational needs (SEN) in Northern Ireland (NI) has not been a visible feature of policy discourse, even though the number of these pupils has increased at a rate that is proportionally higher than the general school population. To better understand the prevalence of SEN, this paper utilises secondary educational data collected between 2010/11 and 2021/22 to interrogate trends in NI as well as relative to other jurisdictions. Findings identify the intricacy of comparative analysis, not least due to differing approaches to data collection and reporting, as well as approaches to assessment and identification of SEN. More specifically, within the NI context, the findings identify fundamental trends across school types. The association between these trends and significant policy changes in how SEN is identified, recorded and reported is critically considered. The utility of big data is discussed, including implications for generating robust evidence, contributing to forward-planning on the future monitoring of, and provision for, SEN, and reinforcing the need for accessible new data to improve the visibility of SEN in the region.