Interdisciplinary Research into Iron Metallurgy along the Drava River in Croatia - The Trans FER Project presents the results of the scientific project 'Production of Iron Along the Drava River During Antiquity and Middle Ages: Creation and Transfer of Knowledge, Technology and Commodities - Trans FER project (IP - 2016 - 06 - 5047)' funded by the Croatian Science Foundation. The research presented explores the evidence for and nature of iron production in the lowland area of the central Drava River basin in Croatia during late Antiquity and the early Middle Ages, from the turn of the 4th to the early 9th centuries. The wide-ranging methodology of the project features non-destructive archaeological site identification (surface survey and geophysics), archaeological excavation of sites with attested bloomery iron production and processing along with their associated dwelling and settlement structures, as well as experimental archaeology. The record of bloomery iron production and processing is explored via an interdisciplinary approach which examines the technology used as well as the natural resources (bog iron ores, wood and plant remains) exploited in the production process. The results of the research testify to the importance and longevity of iron production in the area of the Drava river valley.