Agnes was the daughter of
Rudolf von Rheinfelden, duke of Swabia, and
anti-king of Germany, and his wife
Adelaide of Savoy. Her sisters were
Bertha of Rheinfelden, countess of Kellmünz, and
Adelaide of Rheinfelden, queen consort of Hungary. In 1079, shortly after her mother’s death. Agnes married
Berthold II of Zähringen. After the deaths of her father, Rudolf, in 1080, and her sister, Adelaide, and her brother,
Berthold of Rheinfelden, who both died in 1090, Agnes inherited much of the property of her natal dynasty. Agnes was the founder of the
abbey of St. Peter in the Black Forest, burial site for members of her husband’s dynasty (the Zähringer). Agnes and her husband died within a few months of each other in 1111. They were both interred at St Peter in the Blackforest, an abbey they founded, which became the main burial place for their dynasty. ==Marriage and children==