The chief function of the department is to ensure that standard procedures are followed in procuring goods and services for all of the City's departments and also the Board of Education. The activities of the department are guided by the Purchasing Ordinance which spells out regulations governing purchasing and was passed as legislation by the City's legislative body, the Board of Representatives.

The department is usually the first point of contact that vendors and potential vendors have with the City before doing business with any particular department.