This monograph provides a brief introduction to the material history of Ostia, Rome's harbour town from ca 300 BC until ca AD 600, before centering on about one hundred Latin as well as some Greek inscriptions, some of which are previously unpublished. It focuses on inscriptions which are still present in situ, in forty-two places. They range in date from ca 100 BC until ca AD 420. They belong to and cast light upon buildings, monuments, urban spaces and tombs. Some of them were reused in floors after ca AD 250. Each inscription is presented in full, supplemented by abbreviated names and words, translated into English, dated and commented upon from a contextual point of view. Sometimes inscriptions that are not in situ, as well as relevant ancient texts, are quoted and translated in order to sketch a broader picture. The comments are based on a critical evaluation of the most recent archaeological, historical and epigraphic publications. Several new interpretations result from own research. The inscriptions cast light upon political, socio-economic, religious (pagan and Christian), and funerary aspects of the multi-ethnic Ostian society, its relation with Rome and the Mediterranean world. The publication is intended not only for scholars, teachers and students, but also for historians, classicists, philologists, linguists, epigraphists, archaeologists and art historians. It may also prove a useful vademecum for those who intend to visit or have visited Ostia Antica.