Mitochondria perform diverse yet interconnected cellular functions and are dynamically regulated by complex signaling pathways. Interest in this fascinating organelle has recently undergone a renaissance due to a series of discoveries revealing that mitochondrial function goes beyond the generation of molecular fuel. This Timeline highlights some of the groundbreaking events over the last 30 years in our understanding of how mitochondria are made and turned over, and how they integrate and signal within the cell and organism. To view this Timeline, open or download the PDF.