There are many societies and organizations that may have information of value to your genealogical research. National societies in Ontario are listed in the Societies section of the Canada Research Outline (34545). The most important genealogical society specializing in Ontario is the Ontario Genealogical Society, formed in 1961. It has branches in most counties and districts of Ontario.
Names and addresses of other local historical societies and lineage and ethnic organizations are arranged by county in:
Directory of Heritage Organizations and Institutions in Ontario. Revised Edition. Willowdale, Ontario: Ontario Historical Society, 1992. (FHL book 971.3 C44o; not on microfilm.)
You can find many Ontario Genealogical and Historical societies online at: http://www.daddezio.com/society/hill.ca/SH-ON-NDX.html