I am not sure I would call them requirements, but you must be Catholic and single. That's about it for pre-requisites. Then you decide what order you want to belong to. They all have different charisms. Some are more strict than others. You go through a period called postulancy in which you petition the order to become one of its members. Then you go through novitiate, a training period. At the end of novitiate if you still wish to join the order and the hierarchy of the order feels you would fit in you take vows of profession which usually involve promising poverty, chastity and obedience.

There is a clearly defined hierarchy in religious houses. Usually a Mother Superior is in charge. Nuns cannot ( Bless) other nuns. I never heard of this. certainly religious superiors get their share of saluatations and ceremonial greetings, but that is not the same, as say one Knigh promoting another to say, Baron. Nuns are NOT ordained priest-equivalents thus do not fall under the sacrament of ordination. Only a Bishop can ordain priests. Nuns, after passing though what is called he postulancy- are in fact raised to the status of sister, but I am not sure who performs this honor. My Guess the Mother Superior of the convent= sometimes called reverend mother, or similar titles.

Answer: Definition There is actually a canonical difference between a nun and a sister in the Catholic Church: nuns are those who belong to those religious orders which existed before the Reformation (e.g. Carmelites, Poor Clares, Benedictines) and tend to be enclosed. After the Reformation groups established have been called religious congregations and their members "sisters" not "nuns"; however, in common parlance their is no distinction. Procedure All those seeking to embrace the religious life go through a somewhat similar process, although religious congregations tend to have more leeway than religious orders. Visitation: This is when the person spends short periods of time in the community she wishes to join. This is not a canonical requirement but is common practice. Postulancy: This asts between 6 months and 1 year and is a time when the person continues to discern God's will, but lives in community. She is not, however, a member of the community. Noviate: The novitiate lasts between 1 and 2 years, and every novice is an official member of the community, wearing the habit (normally different from full members). Novitiate is a period of learning more about the spiritual charism and apostolate of the community as well as spiritual growth. Temporary vows: These are taken after novitiate, and are normally renewed annually for a period of 3-5 years. In most communities vows permits a member to have an active vote in the affairs of a community, but the woman may or may not be allowed to hold office. If, during this period, a woman decides to leave the community, she may do so quite freely and normally this is done through her local superior. Final vows: These are considered binding for life and are taken anytime between the 3-5 year period mentioned. Final vows means that a person has all the rights of membership of the community, and those in final profession may serve in office e.g. novice mistress. Release from final vows can come only from the Superior/Minister General of the order. The purpose of a lengthy period is to ensure, as far as possible, that the person seeking to become a nun/sister is happy with the decision and is suited to the life. The whole process is one of prayerful discernment, seeking the will of God which is what ultimately brings true joy and peace.