The founding of the Theosophical Society and initiation of the I AM Activities preceded the giving of the Ascended Master teachings.
Theosophical Society:
https://en.m.wikipedia.org/wiki/Theosophical_Society
I Am Activities:
https://en.m.wikipedia.org/wiki/%22I_AM%22_Activity
Who are the Ascended Masters?
https://templeofthepresence.org/Main/who_are_the_ascended_masters
https://templeofthepresence.org/Main/Ascended_Masters
https://www.templeofthepresence.org/Main/ascended_master_teachings
https://templeofthepresence.org
There are other organizations that provide access to the Teachings of the Ascended Masters, but their information is not entirely up to date. This said, however, they’ve had many years to organize their material and can provide (perhaps even ‘overly extensive’) exposure to Ascended Master Teachings.
http://encyclopedia.summitlighthouse.org/index.php/Special:AllPages
http://encyclopedia.summitlighthouse.org/index.php/Special:Search
Supplementing and grounding the above organizations is the Ascension-Research site:
http://www.ascension-research.org/am-index.html
http://www.ascension-research.org/masters-angels.html
http://www.ascension-research.org/amsearch.html