I am a lay Dominican, so I can tell you a little about the Lay Fraternities of St. Dominic, which is a branch of the Order of Preachers (otherwise known as the Dominican Order). Actually, you don’t have to be married to be a member. You can be single or married, man or woman, as long as you are in good standing with the Church and are willing to live your life according to the spirituality of the Order. As a member of the Lay Fraternity, you share in the mission of the Order, which is to defend and preach the Word of God and the Catholic Faith for the salvation of souls. You do this while you continue to do your career and secular job, and live your life as a family man, a professional, or an ordinary worker in the world.
As a lay member you are not required to make any vows, but you will need to make a promise to live according to the rules of the fraternity and the spirit of the Order. You will also have special duties. For example, you need to say at least the Morning and Evening Prayers found in the Liturgy of the Hours every day, at least 5 decades of the Holy Rosary daily, attend the fraternity meetings monthly, and a few more. You must also have some kind of apostolate that is aligned with the mission of the Order. You don’t need to be an ordained deacon in order to preach the Faith. You may have a blog in the Internet, teach CCD in schools, be a counselor in your Parish or assist in the RCIA program, etc.
As a lay member of the Order, we don’t wear any habit. We dress with our regular clothes, or work clothes. However, we wear a small scapular that is placed inside our clothing, so it is not visible to others. Also, we don’t live in a priory, convent, or monastery. We live in our own homes and with our families.
Unlike vows which bind under pain of sin, the promise does not bind under pain of sin. However, it is a serious matter and should not be taken lightly. Because the promise is serious, a period of formation is required before you are allowed to make your promise. After a period of postulancy (6 months at least), you will be received in the order as a novice. Then you have to undergo another period of formation before you are allowed to make your temporary promise (generally for three years). Your formation (or training) continues during this time. Only after the duration of your temporary promise has passed will you be allowed to make a perpetual promise. This is pretty much like the temporary and permanent profession made by the sisters and brothers in the religious Order.
Being a lay Dominican is not the same as being a member of just any religious society, like the Legion of Mary, the Holy Name Society, etc. As a lay Dominican, you are canonically a part of a religious Order, the Order of Preachers.
I described the lay branch of the Dominican Order for you. But the Franciscans, the Carmelites, the Augustinians, etc. also have their own lay branches. You need to discern your vocation, and pray much, to find out where God is leading you to go. To learn more about the fraternities, or to find a fraternity near you, just google “Lay Fraternities of…” say the Dominican Order, Franciscan Order, etc.