The transformation from an anoxic to an oxygenated world was initiated over 3 billion years ago by the innovation of a new metabolism: oxygenic photosynthesis, which produces oxygen as a by-product. But global oxygenation was a complex transition involving multiple stages over a period spanning more than a quarter of the Earth’s history. We invite contributions from diverse disciplines to examine the timeline of microbial evolution from the Archean/Proterozoic to early Phanerozoic in light of the multiple stages of oxygenation. Topics include but are not limited to: 1) the evolution of metabolisms based on biosignatures in the rock record including contributions from organic geochemistry, trace metal and stable isotope geology and geochemistry, 2) evolution of oxygenic and anoxygenic photosynthetic organisms and impact of oxygenation on microbial aerobic metabolisms of carbon, nitrogen and sulfur and other life-essential elements, synthesizing insights from the ecophysiology of extant microorganisms, molecular clock approaches and fossil/biomarker evidence, and 3) quantitative modeling constraining the timeline for life evolution under different geological and chemical scenarios.