Biological tissues are active materials that undergo a significant shape change during development executed by cellular processes such as cell rearrangements. In this way they are reminiscent of soft amorphous solids, such as colloidal glasses (toothpastes), dense emulsions (mayonnaise) or foams. However, tissues also actively grow, generate and respond to mechanical stresses, and develop morphological patterns through cell signaling and mechanical interactions. Our group is interested in the relationship between mechanics of developing tissues and their structural properties that are mediated by the active cellular processes. To this end, we develop theoretical concepts and tools that are applied and tested in exeprimental systems of our collaborators at Max Planck Institute for Cell Biology and Genetics in Dresden, TU Dresden and EPFL in Lausanne.