As a progressive for his time, Messmer opposed segregationist church policies based on race or language, and he was a major supporter of expanding Catholic-run welfare programs.

[1] After Messmer arrived in New Jersey in September 1871, Bayley appointed him as professor of theology at Seton Hall College in South Orange, remaining there until 1889.

[6] In addition to his academic duties, he served as one of the secretaries of the Third Plenary Council of Baltimore (1884) and as pastor of St. Peter's Parish in Newark (1885 to 1886).

[1] Messmer then went to Rome to study at the Pontifical Roman Athenaeum Saint Apollinare, where he received a Doctor of Canon Law degree in 1890.

After finishing his degree, Messmer served as a professor of canon law at the Catholic University of America in Washington, D.C., for one year.

[7] He also invited Abbot Bernard Pennings to establish the Norbertine Order in the United States, which led to the founding of St. Norbert College in De Pere, Wisconsin.

The Conservatives wanted to maintain church services and parish school instruction in German and other ethnic language.

Its editor, Michał Kruszka, consistently complained about the lack of Poles in the archdiocesan Catholic hierarchy, then dominated by Germans.

In 1913, he assisted the School Sisters of Notre Dame in their founding for women of Mount Mary College in Milwaukee.

[11][8]Messmer was an opponent of Prohibition movement, which looked to ban the manufacture and sales of most alcoholic beverages in the United States.

Messmer issued a pastoral letter in 1918, declaring,"[People] fail to see the absolutely false principle underlying the movement and the sinister work of the enemies of the Catholic Church trying to profit by this opportunity of attacking her in the most sacred mystery entrusted to her.