The Union of Students in Ireland (USI) is the national representative body for the 374,000 students enrolled in third level education across the Island of Ireland. As a membership organization, USI works closely with affiliated Students' Unions throughout Ireland, both in the North and the South. USI operates as a democratic organization, with its supreme authority vested in Comdháil (Congress).

Comdháil is representative of each affiliated students' union, with voting power apportioned based on the size of the student body in each union. Additionally, each union appoints one voting member to the executive body of USI, known as Comhairle Náisiúnta (National Council). USI focuses on various areas of concern and provides support through campaigns, policies, and services.

These include addressing the cost of college, workers' rights and equality issues. They also advocate for the rights of mature students, students with disabilities, and postgraduate students. To stay connected with students, USI organizes events and student achievement awards, keeping members informed through their website and newsletter.

Overall, USI is dedicated to ensuring the welfare and representation of students across Ireland's third level education landscape