The Poor Clares, officially the Order of Saint Clare, originally referred to as the Order of Poor Ladies, and also known as the Clarisses or Clarissines, the Minoresses, the Franciscan Clarist Order, and the Second Order of Saint Francis, are members of an enclosed order of nuns in the Roman Catholic Church. The Poor Clares were the second Franciscan branch of the order to be established. Founded by Clare of Assisi and Francis of Assisi on Palm Sunday in the year 1212, they were organized after the Order of Friars Minor, and before the Third Order. As of 2011, there were over 20,000 Poor Clare nuns in over 75 countries throughout the world. They follow several different observances and are organized into federations.

Enclosed religious orders are religious orders whose members strictly separate themselves from the affairs of the external world. The term cloistered is synonymous with enclosed. In the Catholic Church, enclosure is regulated by the code of canon law, either the Latin code or the Oriental code, and also by the constitutions of the specific order. It is practised with a variety of customs according to the nature and charism of the community in question. This separation may involve physical barriers such as walls and grilles, with entry restricted for other people and certain areas exclusively permitted to the members of the convent. Outsiders may only temporarily enter this area under certain conditions. The intended purpose for such enclosure is to prevent distraction from prayer and the religious life and to keep an atmosphere of silence.