The sacramentary from the Tyniec Abbey near Kraków, which is now in the National Library of Warsaw, impresses with its magnificent design with almost fifty decorative pages of text and pictures as well as rich initial decorations. When it originated in Cologne in the 11th century, relations between Cologne and Poland were very close: Queen Richeza from the Ezzone family, who lived near Cologne, was married to Poland in 1013. Her son Casimir the Renewer reestablished the war-destabilized rule around his seat in Krakow from 1041 onwards, with the support of Cologne and the emperor. The Cologne Sacramentary in Poland exemplifies these connections. At the same time, with the group of medieval manuscripts around the sacramentary from Tyniec, Cologne's Ottonian book illumination experienced an artistic reorientation. The volume presents new research results on the manuscript, its origin and its artistic scope as well as the history of Poland around the middle of the 11th century. Further contributions are devoted to the people involved on both the Cologne and the Polish side, as well as the architectural evidence under Casimir and the early Piasts.