Book of Common Prayer (page 13)

Concerning the Service
of the Church

The Holy Eucharist, the principal act of Christian worship on the Lord's
Day and other major Feasts, and Daily Morning and Evening Prayer, as
set forth in this Book, are the regular services appointed for public
worship in the Church.

In addition to these services and the other rites contained in this
Book, other forms set forth by authority within this Church may be used.
Also, subject to the direction of the bishop, special devotions taken
from this Book, or from Holy Scripture, may be used when the needs of
the congregation so require.

For special days of thanksgiving, appointed by civil or Church
authority, and for other special occasions for which no service or
prayer has been provided in this Book, the bishop may set forth such
forms as are fitting to the occasion.

In all services, the entire Christian assembly participates in such a
way that the members of each order within the Church, lay persons,
bishops, priests, and deacons, fulfull the functions proper to their
respective orders, as set forth in the rubrical directions for each
service.

The leader of worship in a Christian assembly is normally a bishop or
priest. Deacons by virtue of their order do not exercise a presiding
function; but, like lay persons, may officiate in the Liturgy of the
Word, whether in the form provided in the Daily Office, or (when a
bishop or priest is not present) in the form appointed at the Eucharist.
Under exceptional circumstances, when the services of a priest cannot be
obtained, the bishop may, at discretion, authorize a deacon to preside