The JMB represents the boards of management and school management in almost 400 voluntary secondary schools in the Republic of Ireland. The JMB provides support, advice and representation to voluntary secondary schools on all matters relating to school management.

The JMB is the umbrella body for the Association of Management of Catholic Secondary Schools (AMCSS) and the Irish School Heads' Association (ISA) which represents the Protestant schools in the State.

The JMB participates actively in various National Committees involved in policy and decision-making in Irish Education. The JMB negotiates on all management issues such as contracts of employment and employer / employee relations. It represents the voluntary secondary schools in negotiations on all issues at national level which affect the management of schools.