Annum Sacrum (meaning Holy Year) is an encyclical by Pope Leo XIII on the consecration of the entire world to the Sacred Heart of Jesus. It was delivered in Saint Peter's Basilica in Rome on the 25th day of May, 1899, the twenty-second year of his pontificate.
The consecration in the encyclical entered new theological territory by consecrating non-Christians. The encyclical, and the consecration, were influenced by two letters written to the pope by Sister Mary of the Divine Heart who stated that in visions of Jesus Christ she had been told to request the consecration.
The encyclical includes the Prayer of Consecration to the Sacred Heart composed by Leo XIII.