Roman Catholic homilies focus on the Gospel of Mark in Year B; however, during the Easter season, homilies reflect on the Gospel of John in Years A, B and C. The Lectionary of the Catholic Church changes at the end of each liturgical year during the Feast of Christ the King.
The liturgical calendar is made up of six seasons: Advent, Christmas, Lent, Triduum, Easter and Ordinary Time. Homilies often take the liturgical season into account, as well as the Gospel reading. Additionally, the Pope may dedicate certain years, seasons or months to a particular theme; for example, July 2015 was dedicated to the Precious Blood of Jesus.
A homily may also reflect important occasions, such as solemnities, feast days or memorials. These celebrations occur at the same time each year and do not depend upon the Lectionary cycles. A feast day celebrates the life of a saint. For example, September 5 is the feast day of Blessed Mother Theresa of Calcutta; a priest may preach about her life and works on that day.
A solemnity is a very important celebration of great events in the life of Jesus or the lives of certain saints. Some examples of solemnities are Easter, All Saints Day, Christmas, Corpus Christi and the Feast of the Ascension. As with feast days, solemnities often inspire the homily. Memorials are not as important as solemnities and feasts and may not feature as strongly in the homily.