Primitive Baptists, also known as Hard Shell Baptists or Anti-Mission Baptists, are conservative, Calvinist Baptists adhering to beliefs that formed out of the controversy among Baptists in the early 1800s over the appropriateness of mission boards, Bible tract societies, and temperance societies.

This controversy over whether churches or members should participate in mission boards, bible tract societies, and temperance societies led the Primitive Baptists to separate from other general Baptist groups that supported such organizations, and to make declarations of opposition to such organizations in articles like the Kehukee Association Declaration of 1827.

Primitive Baptist churches arose in the mountainous regions of the southeastern United States, where they are found in their greatest numbers.

Primitive Baptists hold Calvinist views and are characterized by "intense conservatism".

Since arising in the 19th Century, the influence of Primitive Baptists has waned as "Missionary Baptists became the mainstream"