Popular piety, as defined in the Directory on Popular Piety and the Liturgy issued by the Congregation for Divine Worship and the Discipline of the Sacraments in 2001, means the various forms of prayer and worship that Christians practice either singly or in community and that are inspired by their culture rather than by the liturgy.
The Catholic Church has declared popular piety "a true treasure of the People of God" and decried the attitude of "certain persons concerned with the care of souls who scorn, a priori, devotions of piety which, in their correct forms, have been recommended by the magisterium, who leave them aside and in this way create a vacuum which they do not fill."
The Second Vatican Council asked that popular Catholic devotions "should be so drawn up that they harmonize with the liturgical seasons, accord with the sacred liturgy, are in some fashion derived from it, and lead the people to it, since, in fact, the liturgy by its very nature far surpasses any of them."
During the Middle Ages the public functions of the Church and the popular devotions of the people were intimately connected. The laity assisted at the daily Liturgy of the Hours psalmody, the sacrifice of the Mass, the numerous processions, and were quite familiar with the liturgy. Those few religious practices outside of official services, e.g. the Rosary (a substitute for the 150 Psalms) originated in the liturgy.
At the beginning of the modern period, "the primacy accorded to contemplation, the importance attributed to subjectivity and a certain ascetical pragmatism exalting human endeavour ensured that Liturgy no longer appeared as the primary source of the Christian life in the eyes of men and women advanced in the spiritual life." The reform of the Roman liturgy after the Council of Trent brought advantages such as ensuring that the doctrinal content reflected the faith in its purity, but its new fixity made it seem the reserve of the clergy and reinforced a division between liturgy and popular piety.
Popular devotion then followed its own channels, especially since the 16th century. Non-liturgical practices like the Stations of the Cross, the Forty Hours' Devotion, various litanies and rosary-based prayers and chaplets prevailed everywhere; novenas and series of Sundays and weekdays in honour of particular saints or mysteries were instituted.