BIG4 is a global consortium to train a new generation of systematic entomologists with broad profiles amalgamating classical aspects of biosystematics with the cross-disciplinary methodological innovations. Evolution of insects from the four biggest orders (1. beetles; 2. bees, ants and wasps; 3. flies and mosquitoes; 4. moths and butterflies) is at the core of BIG4. These ‘big four’ insect groups constitute about half of all living species on Earth and have an enormous impact on natural or anthropogenic ecosystems, even when not visible as such by a layman. Our research and training program consists of 15 individual projects, either taxonomically restricted to any of the ‘big four’ or cross-taxonomic. All projects overlap methodologically along such themes as: large data sets assembly and analyses; phylogenetics; genomics; advanced biodiversity data publishing, and citizen science. By arming students with a variety of methods and skills applicable in academic research and industry from the start of their career, BIG4 enhances knowledge, sustainable use and preservation of the fascinating insect diversity.