Active members meet once a week for prayer, planning and discussion. Between weekly meetings, working in groups of two or more, they engage in specific acts of charity and evangelization. These activities are discussed and approved under the guidance of the Praesidium's spiritual director, who is named by the pastor. The Legion is, in essence, an extension of the heart and hands of the pastor.

Through a balanced program of prayer and service, members become instruments of the Holy Spirit . Works may include personal evangelization, parishioner visitation, prison ministry, visitation of the sick or aged, religious education, visiting the newly baptized, Eucharistic adoration, and meeting the other spiritual needs of the parish community.

The Legion of Mary is open to all Catholics who: