Saint Paul's was built to provide services in English for the rapidly growing first- and second-generation Irish and German Roman Catholic population of Butler. The long nave, transept, tall slender steeple at the southeast corner, and generally restrained decoration are all hallmarks of the English Gothic style employed by John Comes. The church was constructed of Butler sandstone quarried within the city limits and laid by local mason John Hobaugh. The extraordinary jeweltoned stained glass windows were designed by Leo Thomas for his uncle, George Boos's Munich firm. All the interior furnishings and statuary were specified by the architect. Comes designed over sixty buildings, including churches, schools, convents, and rectories from California to New York. The majority of his works are in Pittsburgh and the surrounding areas. Although best known for his revival of Italian Romanesque, Comes did not confine himself to any particular style.