Research in the Keutsch group is aimed at improving our understanding of photochemical oxidation processes of volatile organic compounds (VOCs) that produce tropospheric ozone and are central to secondary organic aerosol (SOA) formation. O3 and aerosol are important secondary pollutants that affect human health and climate, and uncertainties in the radiative effects of aerosol comprise the largest uncertainties in current estimates of anthropogenic forcing of climate. Our scientific approach builds on enabling new field observations of key VOC oxidation intermediates (OVOCs) via instrumentation and method development. Formaldehyde and a-dicarbonyls are examples of target species we have selected that are directly relevant to O3 and SOA formation, but can also act as powerful indicators for overall VOC oxidation processes. We combine these field observations, taken during collaborative field campaigns, with laboratory studies of kinetics that provide new detailed chemical information, in order to test and improve existing atmospheric chemistry models. Our field and laboratory observations and scientific analysis are then made available to the wider atmospheric sciences community. In addition, organic synthesis of oxidation intermediates is often central to unraveling complex oxidation mechanisms and also required to provide authentic standards needed for quantification of these compounds in the atmosphere. A central goal of research in the Keutsch group is the testing and improvement of the mechanistic understanding of secondary pollutant formation across all relevant spatial and temporal tropospheric regimes. To this end our field studies utilize both ground-based and airborne measurement platforms and we plan to extend these studies to the oceans. We are particularly interested in improving the detailed mechanistic understanding of anthropogenic influence on tropospheric chemistry at a global scale and study regions of interest span from urban areas to remote tropical forests, from tropical oceans to the polar regions, and our laboratory studies are aimed at reproducing this range of conditions.