It is normally held in the early morning, often — always in monasteries — preceded by the midnight office, and usually followed by the First Hour.
In the Russian tradition, an all-night vigil is celebrated every Saturday evening, typically abridged, however, in spite of its name, to as short as two hours.
In the Greek parish tradition, orthros is normally held just before the beginning of the divine liturgy on Sunday and feast day mornings.
The akolouth (fixed portion of the service) is composed primarily of psalms and litanies.
During great lent and some of the period preceding it, some of the portions from the octoechos and menaion are replaced by hymns from the triodion and during the paschal season with material from the pentecostarion.