The primary goal of this thesis is to collect, record and interpret the available coin evidence from the territory of modern Bulgaria during the late Hellenistic and early Roman Imperial period, from an archaeological, historical and numismatic perspective. In so doing the work documents the transition and integration of the monetary system of ancient Thrace to that of the Roman world. The evidence examined covers over 250 years, from the establishment of the province of Macedonia in 146 BC down to the reign of Trajan (AD 98-117). Of foremost importance in this process are the introduction, distribution and use of the denarius in the local coin market. The evidence under study was collected from the area of ancient Moesia and Thrace, an area recognized as a frontier zone in the early Roman Empire. Previously Thrace was never the subject of a comprehensive numismatic study that integrated the existing archeological and historical record for such a critical period of time. The purposely studied coin finds (both hoards and single coins, over 48,000 pieces) allowed for the application of statistical analysis to the coin data, revealing important military, economic and fiscal tendencies. The results document a culture well accustomed to the use of coins as means of payment long before the arrival of the Roman currency. Given these circumstances, it is no surprise that as denarii were introduced during the 1st century BC, the market quickly adjusted to new economic relations. Tracing the regional use and distribution of coins, the study bears witness to how local communities benefited from their strategic location and native resources. The main contribution of this work lies in the systematic comparison between the Late Hellenistic, Thracian, Celtic and Roman coinages that circulated together in a region that was of great strategic importance to the Roman Empire. Mechanisms of introduction and acceptance of Roman coins as financial tools have been documented and interpreted both from a chronological and geographical standpoint. Based on comprehensive analyses, this thesis concludes that the nature of the Thracian and Moesian society and economy, as well as the supply of coins, followed the Imperial and interregional trends as an integral part of the Roman Empire.