[3] The county was founded in 1848 and named after Mathew Caldwell, a ranger captain who fought in the Battle of Plum Creek against the Comanches and against Santa Anna's armies during the Texas Revolution.

[4] Caldwell County, of Green DeWitt's petition for a land grant to establish a colony in Texas, was approved by the Mexican government in 1825.

In 1839, Edmund Bellinger became the first settler of Prairie Lea, the county's oldest town.

Several hundred men from Caldwell County served in the Confederate States Army.

[9] The town of Luling was established in 1874,[10] close to an earlier farming settlement named Atlanta .

John and James Merriwether and Leonidas Hardeman built a gristmill and a sawmill, later known as Zedler's Mills.

[11] The Missouri, Kansas, and Texas completed its track between Lockhart and San Marcos in 1887.

[4] Two years later, the San Antonio and Aransas Pass Railway connected Lockhart and Luling to Shiner.

[13] The Luling Foundation was established in 1927 by Davis to teach diversity in agriculture and improve the lives of farm and ranch families.

A Williams Institute analysis of 2010 census data found about 5.8 same-sex couples per 1,000 households lived in the county.