Within the ERA-PG funded project ExBarDiv (Genomics-assisted analysis and exploitation of barley diversity) we have selected a broad set of ~360 cultivated barley lines to represent the diversity and history of European barley breeding in the 20th century. The genetic diversity of this collection has been analysed using a novel set of ~7000 Illumina iSelect SNP markers derived from barley gene sequences. Trends in the patterning of genetic diversity have been explored in both time (year of introduction in national lists) and space (country of origin). Second, we have tested the utility of this diverse cultivar population and high throughput marker set for discovering useful associations between important quantitative traits and genetically mapped markers. 30 diverse traits have been scored in replicated field trials across Europe and the results compared against the genotype data. Promising marker-trait associations will be presented.