Six quarks and six leptons of different kinds, referred to as flavours, form the modern periodic table of the fundamental building blocks of matter. The Standard Model of particle physics successfully describes these elementary particles and the forces between them. A deeper understanding of the flavour structure of quarks and leptons, of their masses and couplings, is however still missing.Decisive new experiments are about to start in particle physics (LHC, high-intensity flavour facilities). They will test existing theoretical concepts and inspire new ideas. This should allow us to make substantial steps forwards in the construction of the fundamental Theory of Flavour, which is the main goal of this project. Such a theory should allow us to address the following fundamental questions: what is the underlying dynamics differentiating quarks and leptons of different flavour? Is this dynamics related to a new symmetry? How can this new dynamics be tested at low and high energies? These questions are of utmost importance in the context of our search for a new, more fundamental, theory of elementary interactions. They are also key ingredients to understand the strucutre of our Universe. Reaching this goal requires substantial efforts in model building, precision calculations, and phenomenological studies. These different lines of research will be joined in a novel way by the collaboration of the principal investigator with four younger team members. All team members have made, mostly independently, important and often pioneering contributions to the different aspects of this project. The combination of their different expertise in a joint effort is a unique feature of the present proposal.