Mental Health Ireland is a national voluntary organisation which was established in 1966 as the Mental Health Association of Ireland. It is a company limited by guarantee with a voluntary Board of Directors representative of local Mental Health Associations and people with expertise in relevant areas.

There are 104 local Mental Health Associations currently affiliated to Mental Health Ireland. While they are autonomous, they share the mission of MHI and participate in projects organised at national level. Local MHAs are active in assisting to meet the mental health needs of the population of their own areas. MHI is affiliated to the World Federation for Mental Health and to Mental Health Europe.

Mental Health Ireland has at present staffing level of 8 employees at central office as well as 11 Development Officers based in Health Board regions around the country who support the work of local Associations.