Model United Nations is a lunchtime and after school activity for students from Fifth and Transition Year, in which they research, debate and eventually pass resolutions on issues and events that take place in the world around them. The issues and resolutions that arise are the same as the United Nations deal with on a day to day basis, and include such topics as International law, the environment, human rights and the arms trade, to name but a few.

Students form delegations from the 192 member countries, approximately six are chosen by the students, to research, debate and pass resolutions. They practice these within the school; this will help them to hone their skills in their various fields. This practice culminates in an international conference held annually.  This gives the students from Loreto the chance to participate alongside 700 students representing 45 schools from many different countries on both sides of the Atlantic.

Model United Nations has been hugely popular among students in Loreto College since 1996. This is primarily because the students have been so enthusiastic and also because parents/guardians have been so generous in welcoming foreign students into their homes every year.