In 1937, Vaclovas Aliulis (1921-2015) joined the Marian Order. He completed his studies at the Marian Catholic Gymnasium (an independent religious secondary school) in 1940, and at the Kaunas Seminary in 1945. Aliulis became a Catholic priest in 1944.

Aliulis served as a Catholic priest in various Catholic parishes in Lithuania: in Varėna and Marijampolė (1945 to 1948), and from 1948 in a number of parishes in the Vilnius diocese. At the same time, he was secretary (1965-1979) and chair (1980-1990) of the Liturgical and Church Music Commission of the Lithuanian Conference of Bishops. In 1970-1974, Aliulis was vice-rector of the Kaunas Seminary. In 1974, he was dismissed from the position at the demand of the Soviet government. From 1979, Aliulis lectured on theology and the catechism on underground courses for nuns. He participated actively in underground catechisation, and was a lecturer in the Underground Catholic Seminary, which was established to train priests for Catholic churches in Lithuania, Belarus, Ukraine and other Soviet republics. Twenty priests were prepared in the seminary to serve in Catholic parishes. Knowing that during Soviet times the official training of priests in the Kaunas Seminary suffered from frequent intervention by the government, the activity of the Underground Catholic Seminary was important to the church and the community of believers. 

During the times of Sąjūdis (the Lithuanian national movement, 1988-1990), Aliulis was an organiser of the Catholic press. In 1989, he founded the journal ‘The Catholic World’, and was its editor-in-chief. In 1988-1991, he was a member of the Sąjūdis Council. In 1993-1996, he was the superior of the Marian monastery in Rome, and since 1999 the superior of the Marian monastery in Vilnius.