Saint Joseph's Day is marked in some branches of Christianity in honor of Saint Joseph, spouse of Mary, the mother of Jesus and foster-father of Jesus of Nazareth.

It is a feast day in Roman Catholicism, falling on 19 March.

In the Orthodox Church the Feast of Saint Joseph falls on the Sunday after Christmas.

The 11th and 12th of the Divine Praises of the Roman Catholic Church are as follows: "Blessed be the name of Mary, Virgin and Mother. Blessed be Saint Joseph, her most chaste spouse".

Saint Bernardino of Siena was the main proponent of Joseph's veneration in the west, where his feast day was first celebrated in 1621.

Pope Pius IX declared Joseph to be the patron of the Universal Church in 1870, and promoted the "Patronage" (later Solemnity) feast of Saint Joseph on the third Wednesday after Easter.

However, as Joseph was a carpenter (or a builder), he is also the patron saint of workers. Pope Pius XII decided in 1955 to add the optional feast day of Saint Joseph the Worker on May 1st, intentionally coinciding with the international labour day, the May Day.

St. Joseph's day is also the name day for many Josephs, Josephines, etc.

In Spain, the day is a version of Father's Day. In some parts of Spain it is celebrated as Falles (see also).

In Sicily and many Italian American communities thanks are given to St. Joseph ("San Giuseppe" in Italian) for preventing a famine in Sicily during the Middle Ages. The fava bean was the crop which saved the population from starvation, and is a traditional part of St. Joseph's Day altars and traditions. Giving food to the needy is a St. Joseph's Day custom.

Saint Joseph's Day always falls during Lent, and St. Joseph's Day altars and feasts have no meat. However, since the feast day is classed as a solemnity, the requirement of abstinence from meat is technically abrogated, according to Canon Law, even if it falls on a Friday. If the feast day falls on a Sunday, the previous Saturday (March 18) is observed instead, and if it falls during Holy Week or Easter week, it is moved to the Monday after Low Sunday, or eight days after Easter (prior to 1970 the Tuesday after Low Sunday was used as the alternate date).