Posey grew from a 1911 railroad switch on the AT&SF line into a settlement of about 70 people by 1941, and one of its earliest organizations was Immanuel Lutheran Church, whose congregation was composed largely of German immigrants attracted by railroad advertising and speculator promotion. The congregation formed in nearby Slaton in 1915, and as membership grew beyond what private homes could accommodate, its leaders decided to build a church in Posey. Immanuel Lutheran Church was dedicated on September 26, 1920, and as the surrounding area grew, the church grew as well. By the next decade the chapel was too small, so it was rebuilt and dedicated on April 16, 1939. Services were held in German and English until the 1940s. In the 1950s and 1960s, further renovations included remodeled interiors, a remodeled parsonage, a new well, and an education building. The church building consists of a main hall, a tower, and an adjacent educational building connected by a covered walkway. The chapel is a wood-frame and stucco structure with entryways, doors, and windows framed by Gothic archways. Its roof, once shingled, is now covered in sheet metal, and its ends and façade are gabled, with a cast-stone parapet along the roof edges. The tower also has a cast-stone parapet and many Gothic arched windows and gabled windows near the top, suggesting it may once have functioned as a bell tower. The educational building is a simple gabled structure. The congregation celebrated its centennial in 2015.