St. Joseph is the founder of the Poor Clerks Regular (Piarists), a community devoted to the task of educating youth. At an early age Joseph loved to care for children; he gathered them together, conducted religion classes in boyish fashion, and taught them how to pray. After a time of severe illness he was ordained a priest. His zeal found expression as he organized the Order of the Poor Clerks Regular of the Mother of God of the Pious Schools and directed the members in the instruction and rearing of children from poor parents.

While residing in Rome, Joseph endeavored to visit the seven principal churches of that city almost every evening, and also to honor the graves of the Roman martyrs. During one of the city's repeated plagues a holy rivalry existed between him and St. Camillus in aiding the sick and in personally carrying away for burial the bodies of those who had been stricken. On account of his heroic patience and fortitude in the midst of trouble and persecution, he was called a marvel of Christian courage, a second Job. When eighty years old, he was led as a criminal through the streets of Rome by the Inquisition. His life is a consoling example of how God permits misunderstandings and opposition, even from ecclesiastics, to harass noble undertakings. At the time of his death his Order had almost been destroyed. Then, however, it again began to flourish.

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