Landmarkism is a ecclesiological viewpoint held by some Baptists concerning the origin and nature of the church.

Though numerous churches and some organizations use the terms Landmark and Landmark Baptist in their name, there is no identifiable sub-group of Baptists known as the Landmark Baptist Church. A "Landmark Baptist Church" is one that holds the idea of Landmarkism or Landmark ecclesiology. Landmark Baptists trace their origin back to the days of Christ, but the names "Landmarkism" and "Landmark Baptist" arose out of an ecclesiological controversy within the Southern Baptist Convention in the mid-1800's. The leaders of what would become known as the Landmark movement were James Robinson

The impetus for the movement was the publication of Pendleton's "An Old Landmark Reset" in 1854, and the Cotton Grove meeting of Baptists in 1851. The meeting at the Cotton Grove Baptist Church near Jackson, Tennessee sought to answer five questions: "(1.) Can Baptists with their principles on the Scriptures, consistently recognize those societies not organized according to the Jerusalem church, but possessing different government, different officers, a different class of members, different ordinances, doctrines and practices as churches of Christ? (2.) Ought they to be called gospel churches or churches in a religious sense? (3.) Can we consistently recognize the ministers of such irregular and unscriptural bodies as gospel ministers? (4.) Is it not virtually recognizing them as official ministers to invite them into our pulpits or by any other act that would or

The emphasis of Landmarkism is (1) that the church is local and visible only; (2) that the church has had a continuous existence since its organization by Jesus before Pentecost until the present day (sometimes called Baptist successionism or church perpetuity); (3) that the Great Commission was given to the church (local churches) only; and (4) that baptism and the Lord's supper are church ordinances and are only valid when performed by authority of a New Testament (Baptist) church.

Landmark ideas of ecclesiology still exist within the Southern Baptist Convention, but are more closely associated with the American Baptist Association, the Baptist Missionary Association of America, and the Interstate & Foreign Landmark Missionary Baptist Association. Many Independent Baptist churches and most unaffiliated Missionary Baptist local associations also hold this ecclesiology. When a majority of the Southern Baptist Convention refused to apply the logical conclusions of Landmarkism to their institutions (such as totally remodeling their system of mission work), many of the strongest advocates of Landmarkism withdrew in the late 1800's. The Gospel Mission controversy, centering on missionary Tarleton Perry Crawford in China, and the Whitsitt controversy, centering on the historical views of seminary professor William Heth Whitsitt, are considered part of the Landmark controversy within the Southern Baptist Convention.

Some other Baptists, such as Primitive Baptists, hold ecclesiological viewpoints that are very similar to Landmarkism.