The Ontario Small Urban Municipalities (OSUM) is the small urban municipal voice of the Province. OSUM is an integral part of the Association of Municipalities of Ontario and has a number of its Board members which serve on the AMO Board of Directors. Policy and research activities are undertaken by OSUM through the staff at AMO.

OSUM has ensured that matters which affect small urban communities are brought to the attention of the provincial and federal governments. Leadership is provided by the Chair and Board of Directors who are elected annually.