Life on earth is sustained by the process that converts sunlight energy into chemical energy: photosynthesis. This process is operating near the boundary between life and death: if the absorbed energy exceeds the capacity of the metabolic reactions, it can result in photo-oxidation events that can cause the death of the organism. Over-excitation is happening quite often: oxygenic organisms are exposed to (drastic) changes in environmental conditions (light intensity, light quality and temperature), which influence the physical (light-harvesting) and chemical (enzymatic reactions) parts of the photosynthetic process to a different extent, leading to severe imbalances. However, daily experience tells us that plants are able to deal with most of these situations, surviving and happily growing. How do they manage? The photosynthetic membrane is highly flexible and it is able to change its supramolecular organization and composition and even the function of some of its components on a time scale as fast as a few seconds, thereby regulating the light-harvesting capacity. However, the structural/functional changes in the membrane are far from being fully characterized and the molecular mechanisms of their regulation are far from being understood. This is due to the fact that all these mechanisms require the simultaneous presence of various factors and thus the system should be analyzed at a high level of complexity; however, to obtain molecular details of a very complex system as the thylakoid membrane in action has not been possible so far. Over the last years we have developed and optimized a range of methods that now allow us to take up this challenge. This involves a high level of integration of biological and physical approaches, ranging from plant transformation and in vivo knock out of individual pigments to ultrafast-spectroscopy in a mix that is rather unique for my laboratory and will allow us to unravel the photoprotective mechanisms in algae and plants.