When people graduate and leave their school they officially become part of the school alumni. There are many different groups that former members of certain schools and other academic institutions can join once they have left, and it is quite common for people who were especially involved with the school to join and then head up these groups. The phrase school alumni is more often associated with American schools and colleges, whilst in the UK the term old-boy is used more frequently to describe former students, particularly former students of independent schools. However, use of the term school alumni is becoming more frequent thanks to the increasingly common practice of embracing Americanisms.

Schools alumni organisations will frequently arrange events for former pupils of their respective establishments, such as annual dinners which are very popular. Some school alumni organisations will sometimes organise a ball or similar event that all former members of the school and those in contact with the school alumni groups will be invited to. In many cases it is not just former pupils that will be invited to become members of school alumni groups, members of staff that are retiring or moving onto new jobs are also able to join these groups sometimes, although it is less common. In some cases current members of staff for some schools will have a significant role to play in the organisation of school alumni activities.