Religious confraternities with their broad range of activities can be of great interest to students of ecclesiastical history, theology, pastoral care, and paraliturgical forms and rites. Moreover, the records provide intriguing insights into social, economic and cultural problems of their time as well as the contemporary mentalities. While each brotherhood tended to specialize in areas defined in its statute, their members were also active in other spheres of life. This was certainly the case of the confraternities, sodalities and tertiary orders of Sandomierz. Whereas devotional and religious practices were their primary concern, they were also involved in activities which enabled them to generate some income and cover their costs. The religious brotherhoods also made their presence felt in education, the running of infirmaries, poverty relief, and culture.
In the 14th-18th century Sandomierz was the base of twenty confraternities as well as the Franciscan tertiaries. Prior to the reception of the acts of the Tridentine Council by the Polish Church six confraternities had already been active in Sandomierz. The Grand Confraternity of the Literati, St Anne's Confraternity, and the Confraternity of the Poor (at the Church of St Peter), the Vicars' Confraternity at the Collegiate Church of the Nativity of the Blessed Virgin Mary, the Confraternity of the Poor in St Paul's parish, and the Confraternity of the Holy Spirit (at the Church of the Regular Canons of Holy Spirit de Saxe) represented the most common religious societies of the time in Poland. In 1597 the Dominicans founded their own brotherhood, the Confraternity of the Rosary, at the convent of St Joseph. An offshoot of one of the most popular confraternities not only in Poland but also in the whole of Catholic Europe at the turn of the 16th century, it was soon joined by another one, based at the Dominican convent of St Mary Magdalene.
The league of Sandomierz confraternities was greatly strengthened by a new batch of religious societies launched by the Jesuits, who set foot in Sandomierz in 1602. Their confraternities, devised as one of the tools of the Counter-Reformation, soon had no match in terms of numbers and influence both in Sandomierz and its region. The Jesuits propagated in particular Marian sodalities for various social and vocational groups, and later, in the 18th century, Confraternities of Good Death, the Sweetest Heart of Jesus and Divine Providence. The popularity of the individual societies in Sandomierz reflected their strength on the national level, in the two Polish provinces of the Society of Jesus.
At the beginning of the 18th century the Confraternity of St Barbara, similar to the Jesuit brotherhood of Good Death, was established at St Paul's Church. Scapular confraternities, which focused on the promise of the Virgin Mary's special protection in this life and more mercies in the life to come, sprang up at about the same time (eg. the Confraternity of the BVM of the Scapular at the Church of the Holy Spirit). The emergence of religious societies of this type, committed to the twin ideas of a devout life and preparation for a good death, was no doubt greatly influenced by the bleak social climate of the time, the devastations and depopulation caused by chronic wars and unabated natural disasters. The Third Order of the Franciscans is known to have functioned at the Franciscan Reformati Church of St Joseph. Although the Benedictine nuns at St Michael's Church did not run any society of their own, many of them were members of confraternities affiliated to other churches.
The presence of several confraternities in an at best middle-sized town gives rise to questions about their mutual relations. We find that there was both co-operation and rivalry between them, especially in the organisation of some solemn services and religious festivals. The data about the functioning of the religious corporations of laymen is a valuable complement to our reconstructions of the social life of the Old Polish Commonwealth.