Reactive oxygen species are important in cell homeostasis as well as the development of human diseases. However, studies in redox biology have lacked a systematic approach due to deficiencies in the current-state-of-the-art tools for measuring and generating reactive species. It is important to be able to distinguish between particular chemical species, rather than lumping all reactive oxygen species together, and to measure intracellular concentrations with spatial and temporal resolution. We are using our skills in genetic engineering, protein engineering, and computational modeling to develop new tools to measure and generate reactive species with more precise chemical specificity and greater spatiotemporal resolution. Simultaneously, we are devising approaches for rigorous interpretation of signal readouts from currently available tools. We are applying our knowledge of these tools to achieve a more accurate understanding of ROS levels in diseases, which will aid in the development of effective therapeutics.