After the establishment in 1817 of the first Reform Synagogue, the "New Temple Association" of Hamburg, and the publication of its own liturgy in 1819, the movement spread very rapidly across central Europe and was the dominant Jewish denomination in Prussia, Austria-Hungary, and France by the middle of the 19th century.
Schisms and Sects
The provoking nature of the graduation banquet of the first class of the Hebrew Union College, in 1881, as well as the radicalism of Reform's first ideological statement, the Pittsburgh Platform of 1885, led to a major schism among American Reform leaders, ultimately resulting in the creation of the Conservative movement by the more traditional Reform rabbis.
Missions and Expansion
While it never actively proselytized gentiles, Reform's ready embrace of converts, acceptance of mixed marriages, and recognition of children of patrilineal Jewish descent as Jews has greatly increased its numbers.
Exploration and Conquest
With the mass migration of German and Bohemian Jews to the United States beginning in the 1840s, Reform quickly established itself as the major Jewish religious movement in America. It remains the single largest Jewish denomination in the United States today.
The much smaller Reform communities outside of the United States, especially in Canada, Europe, and Israel, tend to be far more traditional in their approach to Jewish law and the classical Hebrew liturgy.