MOSA was founded in 1884 in response to “the need for the general adoption of more definite rules for guarding our great educational establishments from the outbreak and spread of preventable infectious disease”.

In 2019 the Association was 135 years old and today it is a professional organisation concerned with providing medical care for mainly independent schools. Following a landmark decision in 2015, membership was opened to any healthcare professional currently or previously registered with an appropriate, professionally recognised organisation.

This meant that, for example, school nurses were eligible to join as full members and since then a number of nurses have joined including three who are now members of MOSA Council. As a result, the Association has gone from strength to strength with the nurses bringing a new breadth of knowledge and skill to the Association’s activities. The membership now is a mix of general practitioners who are medical officers to schools in their practice areas and school nurses, as well as some non-clinicians working in a school setting such as members of the teaching profession who are eligible to join as associate members.