AMBROSIANS, the name given to several religious brotherhoods which at various times since the 14th century have sprung up in and around Milan ; they have about as much connection with St. Ambrose as the "Jeromites" who were found chiefly in upper Italy and Spain have with their patron saint. Only the oldest of them, the Fratres S. Ambrosii ad Nemus, had anything more than a very local significance. This order is known from a bull of Gregory XI. addressed to the monks of the church of St. Ambrose outside Milan. These monks, it would appear, though under the authority of a prior, had no rule. Their discipline became so slack that an appeal was made to Cardinal Borromeo asking him to reform their houses. By Sixtus V. the order was amalgamated with the congregation of St. Barnabas, but Innocent X. dissolved it in 165o.
The name Ambrosians is also given to a 16th century Anabap tist sect, which laid claim to immediate communication with God through the Holy Ghost. Basing their theology upon the words of the Gospel of St. John i. g ("There was the true light which lighteth every man coming into the world"), they denied the necessity of any priests or ministers to interpret the Bible. The doctrine of the Ambrosians may be compared with the "inner light" doctrine of the Quakers.
See Realencyklopddie, i. 439.