From the US Conference of Catholic Bishops:
Extraordinary Ministers of Holy Communion
Liturgy Guidelines: General Principles
In every celebration of the Eucharist, there should be a sufficient number of ministers of Holy Communion so that it may be distributed in a reverent and orderly manner. Bishops, priests and deacons distribute Holy Communion in virtue of their office as ordinary ministers of the Body and Blood of the Lord. When the size of the congregation or the incapacity of the bishop, priest, or deacon requires it, the celebrant may be assisted by other bishops, priests, or deacons. If such ordinary ministers of Holy Communion are not present, "the priest may call upon extraordinary ministers to assist him, i.e., duly instituted acolytes or even other faithful who have been deputed for this purpose. In case of necessity, the priest may also depute suitable faithful for this single occasion (GIRM 162)."
Extraordinary Ministers of Holy Communion should receive sufficient spiritual, theological, and practical preparation to fulfill their role with knowledge and reverence. In all matters they should follow the guidance of the diocesan bishop ( Norms for the Distribution and Reception of Holy Communion Under Both Kinds for the Dioceses of the United States of America, NDRHC, no. 28). When recourse is had to Extraordinary Minister of Holy Communion, especially in the distribution of Holy Communion under both kinds, their number should not be increased beyond what is required for the orderly and reverent distribution of the Body and Blood of the Lord. In all matters such Extraordinary Ministers of Holy Communion should follow the guidance of the diocesan bishop (IBID).
All ministers of Holy Communion should show the greatest reverence for the Most Holy Eucharist by their demeanor, their attire, and the manner in which they handle the consecrated bread or wine. Should there be any mishap--as when, for example, the consecrated wine is spilled from the chalice--then the affected "area . . . should be washed and the water poured into the sacrarium [ GIRM, 280]." (NDRHC, 29).
Extraordinary Ministers of Holy Communion at St. Helen of the Cross
No one may become an Extraordinary Minister of Holy Communion without first completing the basic safe environment program compliance process (see our Safe Environment Program under Ministries). Once that process is completed you can contact the office to become an Extraordinary Minister of Holy Communion.