A major responsibility of SVdP members involves lifelong growth in many areas.  This includes knowledge of Vincentian spirituality and charism and their integration in a member’s life and ministry.  To be an effective member of the Society, more than a kind and loving heart is needed to serve those in need, though that is a good beginning.  Members need to continually deepen their Vincentian Spirituality and Charism personally.  As a community of friends, Vincentians strive to find Christ hidden in each other and the needy they serve.  Initial training for new members is provided informally by the local Conference.

From the "Manual of the Society of St. Vincent de Paul in the United States" pp. 90-91.

There are three types of membership in the Society:

Active members belong to the Catholic Church and accept the Basic Principles or Charter of the Society.  They are accepted as active members by a Conference, enrolled in it and take part in the life of the Conference.

Associate members are those who sincerely and publicly accept the Society’s basic principles but may or may not belong to the Catholic church.

Contributing members are those who make financial donations to support the Society.  Members do not have to be Catholic.