Red algae (Rhodophyta) are important aquatic primary producers that are one of the most anciently diverged eukaryotic phyla with fossil remains dating back to 1.2 billion years ago. The red algal plastid is widespread in the tree of life as an engine of photosynthesis in microorganisms such as diatoms and red-tide forming dinoflagellates. Red algae are also sources of important human foods such as dulse and sushi wrap and have a multitude of pharmaceutical and industrial applications (e.g., agarose and carrageenans). In spite of their obvious importance, the evolutionary tree of life for red algae is poorly known. The aim of this research is to sample broadly across the major groups of red algae and reconstruct their phylogenetic history. To accomplish the aims of RedToL, the project will: 1) reconstruct a robust phylogeny of 471 red algal species using a combined dataset of 2 nuclear, 4 plastid, and 2 mitochondrial genes, 2) obtain complete sequences for a series of 16 plastid genomes that represent the taxonomic breadth of red algae, 3) make freely available red algal multi-gene and genome data via release to GenBank and a project-specific web site. The RedToL team, which consists of prominent red algal specialists from several generations and who use different methods (from morphology to phylogenomics), will address fundamental questions of red algal evolution and their place in the tree of life. This grant will support training of undergraduates, graduates, and post-doctoral fellows from underrepresented groups, including three international graduate students. The project results will be published in scientific papers and they will be discussed in two grant-supported summer workshops and two advisory board meetings. The workshops will focus on training students to become the next-generation of red algal taxonomists. The project team will also contribute to outreach efforts through various lectures and a dedicated RedToL website.