This book presents the first detailed analysis of the mechanism of translating the Polish past tense into French. Grounded in the field of aspectual research, this study bridges the gap between theory and practice by presenting a set of equivalency rules for Polish past imperfective verb forms and French past tenses. Drawing on a wide selection of Polish literary texts and their translations into French, the author analyses the translation of Polish past imperfective verbs in factual contexts and their actual uses in narration. Using the semantic theory of aspect developed by Stanisław Karolak, the author establishes rules of equivalency for imperfective uses in both languages as well as rules of equivalency between Polish past imperfective verbs and perfect tenses in French (passé composé, passé simple and plus-que-parfait). The translation rules developed in this study can be applied directly in translation practice as well as providing a resource for scholars of the French and Polish languages. Additionally, this book lays the foundation for future contrastive studies on aspect in languages from different language families.