A Blue Mass is a Mass celebrated annually throughout the United States in the Catholic Church for those employed in the "public safety field". The color blue relates to the blue-colored uniforms predominantly used by these services. Similar to the Red Mass, the service honors those who have died in the line of duty and those currently serving as first responders. The Mass is an opportunity for the community to show gratitude to first responders and their families.

Mass is the main Eucharistic liturgical service in many forms of Western Christianity. The term Mass is commonly used in the Catholic Church, Western Rite Orthodoxy, Old Catholicism, and Independent Catholicism. The term is also used in some Lutheran churches, as well as in some Anglican churches, and on rare occasion by other Protestant churches.