The article presents the achievements of professor Aleksandra Cieślikowa in the field of word-formation of proper names. The most important issues concerning the creation of anthroponyms in the Old Polish era selected from monographs and scientific articles are detailed. These issues include the problems of motivation in onomastic word-formation, the onimization process and the way of describing non-derivatized words by word formation and the participation of paradigmatic derivation in the emergence of Old Polish personal names. The views of Aleksandra Cieślikowa regarding Old Polish anthroponymy contributed to the development of onomastic word-formation, an integral part of the grammar of proper names and gave methodological foundations for the description of Old Polish personal names from a synchronic perspective.