The Unitarian Universalist Association was formed in 1961 originating and evolving from Unitarianism when associated with Christianity rejects the Trinitarian understanding of Good. Although there are many antecedents for this specific point of view for the origin of the movement it is usually accepted to be the work of Michael Servetus, and of the Sozzinis (i.e. Socinianism).
The first Unitarian congregation was in England in 1774 and in the United States in 1782, but the movement finally was fully organized in Baltimore in 1819 with the sermon of W. E. Channing on Unitarian Christianity.
The American Unitarian Association was founded in 1825 and existed until 1961 when emerging with the Universalists to become the Unitarian Universalist Association. It is characterized by its desire of wanting its members to seek truth out of human experience rather than allegiance to creeds or doctrines. There is no hierarchal control, each congregation is autonomous. A.G.H.
Source:
Bowker, John. ed. The Oxford Dictionary of World Religions. New York. Oxford University Press. 1997. p. 1005