In 1836 Father Emanuel Thienpont, the first priest to visit Hardin County and one of the earliest missionaries of Ohio, visited the Kenton area and it is presumed that he also came to tend for the Catholic families in Ada. In 1858, Father Sullivan of Tiffin, Ohio held the first recorded Catholic services in Ada. A Father Murphy, also of the Cleveland Diocese, came on occasion. Around 1862 the Superior of the Society of the Most Precious Blood at Minster, Ohio sent priests to Ada at regular intervals.

In June 1866, Reverend Nicholas R. Young was appointed the first resident pastor of the church in Kenton and he took charge of Ada, holding services on the second floor of E.E. Baumann's Grocery Store on the northwest corner of Buckeye and Johnson Streets. Reverend Joseph M. Quatman succeeded Father Young in 1869 and in June 1870 Reverend Nicholas J. V. Fas came to the area.

Church membership grew and the work increased to a degree that Father Fas could not care for the Ada church properly and Reverend Alexander R. Sidley of Lima was called on to serve the parish, which he did for three years. Fire destroyed the first place of worship and services were then held in the homes of the parish members. In 1872 a room was leased on the second floor of the I.O.O.F. Building (Block) and the members worshipped there for several years.

The earliest Catholic families in Ada were A.C. Baker, Michael Flynn, John Morrow in 1856; Daniel Breen 1858; Thomas and Bartholemew Bastabel 1861; Daniel Hanley 1863; Bartholemew O'Leary 1864 and Jacob Forbing 1869. Other early members were the Felkers, the Durbins, the Hogans, and the Klices. The current location of the church and the hall are on two lots of land purchased from John Johnson, son of Ada's founder Samuel M. Johnson. The initial deed to the land was dated August 10, 1874 and was put in the name of Rev. John B. Purcell, Bishop of the Diocese of Cincinnati. Jacob Forbing (date unknown) had previously donated a lot at the southwest corner of Ballard and Johnson Streets on which to erect a church building. This lot was sold in 1874 (with Forbing's consent) and two lots on the corner of Simon and Hoosier (now known as Highland) Streets were purchased, as this was considered a better location.