Methods in Cell Biology Volume 155 provides an update on the step-by-step how-to methods to study mitochondrial structure, function and biogenesis contained in the first two editions. As in the previous editions, biochemical, cell biological, and genetic approaches are presented along with sample results, interpretations, and pitfalls for each method. New chapters in this update include Isolation of Mitochondria and Analysis of Mitochondrial Compartments, Isolation of Mitochondria from Animal Cells and Yeast, Isolation and Characterization of Mitochondria-Associated ER Membranes, Import of Proteins into Mitochondria, Proximity Labeling Methods to Assess Protein-Protein Interactions in Yeast Mitochondria, and more.