In 1926, the property was converted into a Jewish synagogue by two congregations, Teferes Israel and Chevre Kadishe. The two congregations, which were founded by Russian Jews, merged the same year because neither was large enough to maintain a permanent rabbi. The property already belonged to a Jewish family, the Lutwacks, who bought it in 1916. The conversion of the home into a synagogue reflects the transformation of north Hartford into a more ethnically diverse neighborhood in the early twentieth century.
During the time that the Mather building was used as a synagogue, certain architectural changes were made to accommodate its new purpose. An ark for the Sacred Torah scrolls was built on the east wall and a central platform for the reading of the Torah was added. The platform was later removed. As was customary with Eastern European Jews, graven images were not included in the building, which was generally free of any sort of adornment.
In 1954, the building was purchased by the Excelsior Lodge, an African American Masonic lodge dating back to 1859. In the same way that Jewish immigrants transformed the neighborhood in the early 1900s, middle- and upper-class African Americans transformed the area in the mid-twentieth century. The Excelsior Lodge is one of the oldest African American organizations in the city and was active in civil rights and social justice causes in Hartford.