Mt. Calvary Lutheran Church of La Grange, Texas began its origin as a result of the merger of two separate Lutheran congregations, Trinity Lutheran Church and Zion Lutheran church. 

In November of 1891, Pastor G.W. Buchschacher of Warda, Texas began conducting services in La Grange.  In the summer of 1892, the new mission church received its first resident pastor, the Rev. Traugott Zoch, who had just graduated from the seminary in Springfield, Illinois.  It was he who decided that greater opportunity for a congregation lay west of La Grange, and so it was that Trinity was established in the area later known as Trinity Hill.  December 11, 1892, Trinity Lutheran Church was organized.

Thereafter another effort was again made to conduct services in the city of La Grange, without success. However, the Mission Board of the Texas District of the Lutheran Church - Missouri Synod continued efforts to expand mission work in La Grange.  Once again, services were begun in the city.  Some of the services were conducted in the St. James Episcopal Church.  On March 27, 1928, under the leadership of Pastor A.E. Moebus, who at the time was pastor of Trinity, Zion Lutheran Church was organized.  The bulk of the membership of Zion was composed of members who transferred from Trinity, and were largely those that resided in the city of La Grange. 

In 1935 the Church building at Trinity was enlarged by an addition on the east side, but even after the addition, there were no amenities in the building.  There was no plumbing and heating was accomplished by a wood heater.  There was no cooling system, or running water.  One of the customs of the congregation was that the women would be seated on one side and the men on the other.

Both congregations were served by Pastor Moebus until 1939, when each congregation decided to call its own pastor.  This arrangement continued until 1957, when Trinity was unsuccessful in obtaining a new pastor, primarily because membership had dropped radically at Trinity.  Pastor T. H. Graalmann accepted a call to Zion and became their vacancy pastor.  The German services that had been conducted at Trinity with Pastor Graalmann, ceased.  The prospects of obtaining a pastor for Trinity were not promising, and if Zion's pastor would not serve as vacancy pastor, all indications were that Trinity would probably be forced to disband.  Furthermore, the facilities at Zion were inadequate because of the growth of the congregation, and so a new or enlarged structure was required.  Therefore it was decided by both congregations to explore the possibility of a merger of Trinity and Zion.  As a result, in the early part of 1961 members of each congregation were selected by the respective Voters' Assemblies to look into the matter.  Baker Davis, Clarence Peters, and Edgar Roitsch from Zion, and Wilbert Diers, Walter Schneider, and Walter Oeltjen were selected from Trinity.  This committee, under the leadership of Pastor Graalmann, began its work in April of 1961. After four months, a written report was formulated dated August 20, 1961. This report was unanimously agreed upon by the committee from both congregations, and presented to the communicant membership of congregations on August 27 and 28, 1961. 

Voters' Meetings to decide whether to accept the report were scheduled for each congregation on September 10, 1961.  However, Hurricane Carla hit the Texas coast on that date, so the meeting had to be held a week later.  Both congregations accepted the report of the committee.  On December 17, 1961 and on a subsequent date, joint meetings of the Voters' Assemblies were held at Camp Lone Star to approve a constitution and by-laws.  Thereafter, on January 28, 1962, the Voters' Assemblies met at Zion to formally adopt the constitution and by-laws. They chose the new name, Mt. Calvary Lutheran Church of La Grange.  They also decided to elect officers; to transfer all properties to Mt. Calvary; to dissolve the corporations of Trinity and Zion; to incorporate Mt. Calvary; and to select a vacancy pastor. Pastor Graalmann agreed to serve as the vacancy pastor, and was subsequently extended a call, which he accepted, thus becoming the first pastor of Mt. Calvary. 

The next step was to construct a house of worship sufficient to meet the needs of the new congregation. This new church building was dedicated in May 1965. In the years following, a new educational building, new parsonage, and eventually a new church addition were also constructed on the property which previously belonged to Zion. The Zion church building was sold to Peaceful Rest Baptist Church, and is now located in the 800 block of East Fannin Street in La Grange. The Zion teacherage, and the land it was located on, was sold. The Zion parsonage was sold and moved. The Zion parish hall was torn down. The Trinity parsonage, and the land it was located on, was sold. The Trinity church building was sold for the material. The cemetery which was located at Trinity church continues intact, and now operates under the name of Mt. Calvary Lutheran Church Cemetery. 

Pastor Graalmann continued as pastor of Mt. Calvary until 1969. The pastors that served since then are as follows: Rev. Alvin Walter, 1969-1976; Rev. Herbert Wottrich, 1977-1979; Rev. Walter Harting, 1979-1987; Rev. Dennis Bragdon, 1988-2009; Rev. William Qualman, 2012-2018; and Rev. Jason Kaspar, who will be installed on July 31, 2019.

Today the mission of Mt. Calvary Lutheran Church and Preschool, as it is now known, is "committed to reaching out with the love of Jesus".  Toward this goal the members of Mt. Calvary provide for the preaching of the Gospel of Jesus Christ at Mt. Calvary and, by their support of the mission work of the Lutheran Church - Missouri Synod, throughout the world.  Through its various organizations, the congregation offers opportunities for worship, education, fellowship, and service.