The Somerville Auxiliary Fire Department operates under the direction of the Somerville Fire Department. It is a non-paying, non-profit organization whose members volunteer their time, energy and skills to provide support services to the Somerville Fire Department and various city agencies.

Auxiliary Fire Department members also provide services to the Residents of the City of Somerville, and mutual aid assistance to other communities as requested. The delivery of auxiliary fire services is a unique and complex undertaking. It requires service oriented volunteers who posses sound judgment, physical and moral courage, fidelity and personal integrity. Furthermore, providing auxiliary fire services is a team effort. Each member must posses a strong willingness and capability for being an integral part of a team.

The Somerville Auxiliary Fire Department operates two squad units. Each unit being set up for a specific type of emergency as well as being set up as a secondary back up unit. Having this ability gives the auxiliary the flexibility to be ready for the changing conditions during a response.