The Holy Spirit Adoration Sisters (Latin: Servarum Spiritus Sancti de Adoratione Perpetua, SSpSAP) are a Roman Catholic religious institute. The nuns live a contemplative life, focused on perpetual adoration of the Blessed Sacrament, offering intercessory prayers for the world 24 hours a day. Inside the enclosure the nuns wear rose-colored tunics with their habits symbolizing their joy for the Holy Spirit. As a consequence of these habits, the nuns are known colloquially as the "pink sisters".
The congregation was founded in 1896 in the Netherlands by Arnold Janssen, a German diocesan priest who had first founded in 1875 the Society of the Divine Word in the Dutch border village of Steyl, and in 1889 the Missionary Sisters Servants of the Holy Spirit. Later, Janssen formed the Holy Spirit of Perpetual Adoration congregation so that the missionaries that he had already formed could be supported by prayer. Janssen was canonized on October 5, 2003, by Pope John Paul II.
Mary Michael was Janssen's first Holy Spirit of Perpetual Adoration Superior of the convent in Steyl. The first convent abroad was established in Philadelphia, Pennsylvania, United States in 1915 by Mary Michael (Adolfine Tönnies) (1862–1934), upon the invitation of Edmond Francis Prendergast. Mary Michael grew the convents in many locations, where they continued to grow after her death on Feb. 25, 1934 in Steyl. On Feb. 25, 2015 the Holy See gave approval for the beatification process for Mary Michael. The motherhouse was later moved from Steyl to Bad Driburg, Germany.
Currently, there are 22 convents located in Argentina, Brazil, Chile, Germany, India, Indonesia, the Netherlands, the Philippines, Poland, Slovakia, Togo, and the United States. They are supported solely by donations from visitors and other private parties.