Saint Thomas More School opened for the first time on September 15, 1952 with a faculty of three Dominican Sisters of Sinsinawa, Wisconsin. At the time, there were 108 students enrolled in grades one through four. Classes were held in temporary quarters in the Parish Hall while construction of a permanent building was in progress.  In January 1953, classes were moved into the present building. An additional grade was added each year. By 1956, the school served pupils in grades one through eight. The first graduating class received diplomas in 1957.

Five additional classrooms were added by the beginning of the 1963 school year. At that time, the school reached its peak enrollment of 511 students in 13 classrooms. As the student population decreased and space became available, classrooms were converted to a computer lab, music room and Extended Care room. An air conditioning system was installed throughout the school in 1998.

A departmental program for Junior High was introduced in 2001. Lockers were installed to facilitate the movement of students between classes. The computer lab, with a donation from the Knights of Columbus, was completely networked to accommodate a class of 36 students. In addition, there is a computer station with Internet access in each classroom. Two mobile carts, with computers and projectors were acquired in 2007, and a wireless network installed.

Thanks to a bequest by Mildred Harrigan, a long-time parishioner, our Fine Arts program was expanded with the purchase of additional instruments and materials for the Music Program.  In spring 2009, Room 12 was converted into a Preschool Classroom and a Preschool play yard was constructed.
In June, 2011, St. Thomas More School was awarded full accreditation from the Western Association of Schools and Colleges (WASC) and the Western Catholic Educational Association (WCEA) for the second time running. 

In the summer of 2013, the renovation of the field began, which was made possible through a generous grant from the Shea Foundation. On October 1, 2013, the field was blessed and ready to be used by our students. During this time, the Shea Foundation also provided STM with a grant to update our wireless infrastructure and purchased wireless projectors, whiteboards, Apple TVs, and teacher laptops per each classroom, as well as three Mimio interactive touch boards for the junior high classrooms.