The Eucharist completes Christian initiation and is the only repeatable sacrament of the three. The Eucharistic celebration (the Mass) is the source and summit of the Christian life. It is the very sacrifice of the Body and Blood of the Lord Jesus, which he instituted at the Last Supper and entrusted to his Church as a memorial of his death and Resurrection. It is a sign of unity, a bond of charity, a paschal banquet in which Christ is consumed, the mind filled with grace, and a pledge of future glory is given to us. The fruit of the Mass is Holy Communion in which we partake of the Body and Blood of Christ, which we are urged to receive at every Mass, provided we are in the state of grace.
USCCB Guidelines for the Reception of Holy Communion for Catholics, Fellow Christians and Non-Christians