It is important to note there are qualifications to join these societies. To learn what these qualifications are, you can visit their websites or visit the society if it is a local one. Some of them, such as the DAR, will want proof of ancestry to the patriot you descend from. You will need to provide documents that show proof of births, marriages and deaths. Some societies do not require a direct ancestral line, but will let you use a relative, such as great uncles. Each society should have a registrar to assist you in providing the required information, or may, to some degree, offer assistance. There are lineage researchers that will also do this for you for a fee. You can find someone to do this from the Find a Genealogist page on the Board of Certification of Genealogists website or on the Association of Professional Genealogist Directory.
Here are just a few genealogical societies you may wish to consider joining:
