This lecture draws on interviews conducted with staff and students who have made complaints within universities that relate to unfair, unjust or unequal working conditions and to abuses of power such as sexual and racial harassment. It approaches complaint as a form of diversity work: the work some have to do in order to be accommodated. Making a complaint requires becoming an institutional mechanic: you have to work out how to get a complaint through a system. It is because of the difficulty of getting through that complaints often end up being about the system. The lecture explores the significance of how complaints happen 'behind closed doors,' and shows how doors are often closed even when they appear to be opened.