Ash Wednesday is a holy day of prayer and fasting in many Western Christian denominations. It is preceded by Shrove Tuesday and marks the first day of Lent, the six weeks of penitence before Easter.

Ash Wednesday is observed by Catholics, Lutherans, Moravians, Anglicans, Methodists, Nazarenes, as well as by some churches in the Reformed tradition, including certain Congregationalist, Continental Reformed, and Presbyterian churches.

Many Christians attend special Ash Wednesday church services, at which churchgoers receive ash on their foreheads.