Solemn vow

In Roman Catholic canon law, a solemn vow is a vow ("a deliberate and free promise made to God about a possible and better good") that the Church has recognized as such.

Any other vow, public or private, individual or collective, concerned with an action or with abstaining from an action, is a simple vow.

In canon law a vow is public (concerning the Church itself directly) only if a legitimate superior accepts it in the name of the Church; all other vows, no matter how much publicity is given to them, are classified as private vows (concerning directly only those who make them). The vow taken at profession as a member of any religious institute is a public vow, but in recent centuries can be either solemn or simple.

There is disagreement among theologians as to whether the distinction between solemn and simple vows derives simply from a decision of the Church to treat them differently or whether, in line with the opinion of Saint Thomas Aquinas, a solemn vow is, antecedently to any decision by the Church, a more strict, perfect and complete consecration to God.