The Max Planck Institute for Chemical Ecology (MPI-CE) investigates how organisms communicate with each other via chemical signals. We study how plants best adapt to their respective environments and identify the chemical compounds they produce to attract pollinators, fend off herbivores and pathogens, or keep unpleasant competitors away. In the course of evolution, insects have adapted to the survival strategies of plants. We therefore analyze the genetics, physiology and behavior of herbivorous insects. Insects also make use of plant substances to protect themselves against predators: They sequester toxic compounds; some insects even signal by exhibiting their bright colors that they should better not be eaten. Microorganisms play a crucial role in the fitness of plants and insects. Some are pathogens, others are symbiotic partners and help to supply nutrients or boost the immune system. We want to determine who plays which role. The MPI-CE was founded in 1996 and is part of the Max Planck Society. Together with Friedrich Schiller University Jena, it runs the International Max Planck Research School Chemical Communication in Ecological Systems, a graduate school for excellent international graduates.