“Being open to God’s will through prayer and discernment, I felt God was calling me to a vocation in Caritas Christi, a Secular Institute. I knew I wanted to be consecrated to God. I knew that I needed to remain in my current job and to be there for my aging Parents. Not knowing anything about Secular Institutes within the Church, I thought I would make my vows to God and live my life with the vows of celibacy, poverty, and obedience. It was an advertisement for Caritas Christi that opened up my knowledge of this vocation. Rather than be on my own, I was entering into a vocation of Pontifical Right. Church approval and guidelines are extremely important to me. I was also being guided by a sponsor and other members who are my “sisters” in this vocation. It is the promptings of the Holy Spirit that will guide you to the vocation that God has called for you. My good friend has said of this vocation, “God has left her among us.” To be their friends, guide them; a witness of Christ among them. God has called me to a vocation of great joy and love of God and community. How happy I am to do His will.”
-Dian Crane, member of Caritas Christi
In addition to religious institutes or communities, where men or women live in community under religious vows, the Catechism of the Catholic Church and the Code of Canon Law outline several other forms of consecrated or apostolic life. These are sometimes individual callings, and sometimes lived out in community, and vary in their work and vows that are made. They are:

Canon 710 of the Code of Canon Law defines a secular institute as “an institute of consecrated life in which the Christian faithful, living in the world, strive for the perfection of charity and seek to contribute to the sanctification of the world, especially from within.” (emphasis added)

Secular institutes were officially established in 1947 with the Apostolic Constitution Provida Mater Ecclesia of Pope Pius XII.

Members of a secular institute profess the evangelical counsels of poverty, chastity, and obedience, either as vow or promise, but do so while living out their life in the world.
Members of a secular institute are not required to live in common life, and typically live out in the world separate from other members of the institute, but Art. III §4 of Provida Mater Ecclesia states that they must have one or more houses, for their superiors, for formation, and for the ill or elderly in their order who cannot care for themselves. They do however live in communion with each other by their participation in the life of the institute.

Different institutes have different memberships, with some for lay women, lay men, priests, deacons, married couples, or any mix of the above. However, joining a secular institute does not change the other prescripts of canon law for a member. Diocesan priests are still subject to their bishop, being a member of a secular institute does not grant any additional rights within the Church, and those already bound by religious vows as part of a religious order cannot additionally make vows to a secular institute.

The purpose of secular institutes is for those who are not a part of a religious community to live out their service to the Church “in the world and not of the world, but for the world.” (from USCSI website)

“The effectiveness of Institute life in the Christian renewal of families, of secular professions, of society in general, through people’s daily contact, from the inside of the secular scene, with lives perfectly and totally dedicated to God’s sanctifying work in them is obvious. These Institutes also open the way to many forms of apostolate and service in times, places and circumstances from which priests and Religious are excluded by the nature of their calling, or which for other reasons are not accessible to them.” – Provida Mater Ecclesia

United States Conference of Secular Institutes

“Without always professing the three evangelical counsels publicly, hermits “devote their life to the praise of God and salvation of the world through a stricter separation from the world, the silence of solitude and assiduous prayer and penance.”(Can. 603)” – Catechism of the Catholic Church #920

Hermits do not always take vows, but those that do profess the evangelical counsels of poverty, chastity, and obedience to a diocesan bishop or religious superior. Obedience in this sense is to observe a program of living as proscribed by the bishop or superior. When they are not under public vows, hermits typically still live a life of poverty and chastity, and are obedient to their dedication to prayer and penance.
Hermits, by definition, live out their life withdrawn from the world, so as to grow closer to Christ. They are often sponsored by a diocese, religious community, or a member of the faithful to help them with basic needs, and they are sometimes sought out for spiritual direction.
Anybody can be called to live a vocation of eremitic life, even priests and religious, provided it does not conflict with vows, promises, or professions they have made.
A primary work of a hermit is to live out St. Paul’s call in Thessalonians to “Pray without ceasing.” Typically hermits will spend their time living simply so they can devote themselves to prayer and penance for “the praise of God and the salvation of the world” (Can. 603).

““As with other forms of consecrated life,” the order of virgins establishes the woman living in the world (or the nun) in prayer, penance, service of her brethren, and apostolic activity, according to the state of life and spiritual gifts given to her. Consecrated virgins can form themselves into associations to observe their commitment more faithfully.” – Catechism of the Catholic Church #924

A woman living out this vocation has been “consecrated to God by the diocesan bishop according to the approved liturgical rite, are mystically betrothed to Christ, the Son of God, and are dedicated to the service of the Church.” (Can. 604) However, as part of this particular call they do not profess the evangelical counsels.

Rite for the Consecration of Virgins

Consecrated virgins are not required to live in community, however Canon Law states that “In order to observe their own resolution more faithfully and to perform by mutual assistance service to the Church in harmony with their proper state, virgins can be associated together.” (Can. 604 §2)
Both lay and religious women can be consecrated as virgins. In some religious orders, such as the Benedictines or Carthusians, it is part of the formation and profession process maintained by the order, and is done either at the same time as solemn vows or some time after.
The work of consecrated virgins greatly varies, as this is a call for a woman to be “anxious about the things of the Lord, so that she may be holy in both body and spirit” while still carrying out her work in the world.

United States Association of Consecrated Virgins

“Alongside the different forms of consecrated life are “societies of apostolic life whose members without religious vows pursue the particular apostolic purpose of their society, and lead a life as brothers or sisters in common according to a particular manner of life, strive for the perfection of charity through the observance of the constitutions. Among these there are societies in which the members embrace the evangelical counsels” according to their constitutions.” – Catechism of the Catholic Church #930 (from Canon 731)

Societies of apostolic life, by definition, do not take vows in the same way as religious communities. Certain societies, however, do “assume the evangelical counsels by some bond”.(Can. 731 §2) This includes societies that have annual, rather than perpetual, vows, those who make promises of celibacy and obedience while active within the society, or those who are made up of priests who, in addition to their priestly promises, profess an additional oath of fidelity to the mission of the society.
“Members must live in a house or in a legitimately established community and must observe common life.” (Can. 740) A member of a society of apostolic life can live outside the community for at most three years at a time, with the permission of his or her superior. (Can. 745)
Each society is focused on a different membership. There are societies whose members are priests, those who have both priests and lay brothers, those that are only for lay women, only for lay men, or those that are for both lay men and women. Religious cannot also belong to a society of apostolic life, and must have the permission of the Holy See to transfer between a religious institute and a society of apostolic life. (Can. 744 §2)
The work of societies varies greatly. Many societies are focused on missionary work, some within particular groups or areas. Others are focused on promoting a certain spirituality, whether the traditional Latin liturgy, the Charismatic movement, or other forms of Catholic liturgy.