In recent decades, women of the higher nobility ruling and exercising power in the medieval period have increasingly moved to the fore of international research. Attention was paid especially to those queens whose family backgrounds and favourable structural circumstances enabled them to emerge as queens regnant or to rule on behalf of their absent husbands or under-aged sons. These conference proceedings aim to broaden the international research discourse by juxtaposing queens and princesses in the various kingdoms and regions of Europe during the High and Late Middle Ages. Basic considerations on the significance of power in the medieval period are followed by papers on queens and princesses on the Iberian Peninsula, in the principalities of Outremer, in England, France, Upper Italy, the Habsburg Southwest of the Holy Roman Empire and in Tyrol. Specific consideration was also given to the coronation ordines for empresses and queens, to papal epistles to queens and princesses, and to the significance of ecclesiastical princesses ruling from the 11th to the 14th century.