MABAS is a mutual aid organization that has been in existence since the late 1960s. Heavily rooted throughout northern Illinois, MABAS includes over 550 member fire departments organized within 46 divisions. MABAS divisions geographically span an area from Lake Michigan to west of Rockford and south through Champaign-Urbana, Douglas County, St. Clair County, and St. Louis. Four Wisconsin divisions also share MABAS with their Illinois counterparts. Interest is also becoming evident from the Iowa, Indiana, and Missouri bordering communities.

MABAS includes over 25,000+ firefighters and daily staffed emergency response units including more than 750 fire stations, 900+ engine companies, 275+ ladder trucks, 600+ ambulances (mostly paramedic capable), 150+ heavy rescue squads, 125+ light rescue squads, and 225+ water tankers. Fire/EMS reserve (back-up) units account for more than 600 additional emergency vehicles.

MABAS also offers specialized operations teams for hazardous materials (HAZMAT), underwater rescue/recovery (DIVE) and above grade/below grade, trench and building collapse rescues aka Technical Rescue Teams (TRT). An additional element of resource are the certified fire investigators which can be "packaged" as teams for larger incidents requiring complicated and time-consuming efforts for any single agency.

MABAS is a unique organization in that every MABAS participant agency has signed the same contract with their 550+ counterpart MABAS agencies. As a MABAS agency, you agree to: standards of operation, incident command, minimal equipment staffing, safety and on-scene terminology. MABAS agencies, regardless of their geopolitical origin, are able to work together seamlessly on any emergency scene. All MABAS agencies operate on a common radio frequency, Interagency Fire Emergency Radio Network (IFERN) and are activated for response through pre-designed "run" cards each participating agency designs and tailors to meet their local risk need. MABAS also provides mutual aid station coverage to a stricken community when their fire/EMS resources are committed to an incident for an extended period.