The formation of Mutual Aid Committees (MACs) is an integral part of the Home Affairs Department's effort to promote public participation in community affairs. A MAC is a voluntary body formed by the residents of a building.

MACs were promoted initially in private multi-storey buildings, they quickly extended to public housing estates, industrial buildings, temporary housing and squatter areas. By Nov 30 2011, there were 2,243 MACs throughout the territory.

The primary aims of a MAC are to promote a sense of friendliness, mutual help and responsibility among members, and to promote better security, a better environment and, generally, more effective management within the building. These committees provide a channel of two-way communication between Government and the residents on matters affecting the well-being of the individual and the community and also provide a focal point for residents to participate in community activities.

Resident's participation is crucial to the formation and running of a MAC. In order to give general guidance to MACs in conducting their business, two sets of Model Rules have been prepared by the Home Affairs Department: Model Rules for a MAC in a Public Housing Estate and Model Rules for a MAC in a Private Building. They are obtainable at the Public Enquiry Service Centres of the District Offices.