Reconstruction of the Tree of Life, with more than 1.9 million described species, and many more millions undiscovered or extinct, presents a profound scientific challenge. While providing powerful insights into the past, the Tree of Life provides a new lens through which to interpret the patterns and processes of evolution, as well as the ability to predict the responses of life to rapid environmental change. Pam Soltis and I propose three specific activities that address interrelated goals for improving our understanding of the Tree of Life. We will: (1) assemble an international research team with expertise across diverse organisms to reconstruct the tree of all life, with 1 million representative species; (2) construct incrementally larger phylogenies, with an initial goal of 100,000 plant species (two times larger than any published tree) and an ultimate target of all green plant species; and (3) will explore the co-diversification of angiosperms and fungi and address the hypothesis that species diversification in one group triggered similar events in the other.