In this report, Mike Day and Jim Dickinson look at the past, present and future of student unions. Although almost every university has a students' union, there is little research or reliable data on their form, role or successes. They are often seen and judged through a 'student politics' lens and face criticism for being too radical, not radical enough or unrepresentative. To understand today's students' unions -- their role, contribution, critique and opportunity -- requires an understanding of their history. This HEPI report traces their origins from 1088 to the present day and ends by considering their future potential. [Forward by Douglas Blackstock.]