Mitochondria are endosymbiotic organelles that serve as key hubs for apoptotic regulation, metabolism, and cellular signaling in eukaryotic cells. Over 99% of the ~1500 mitochondrial proteins are encoded in the nuclear genome and depend on specific targeting signals to direct them from the site of synthesis in the cytosol to the appropriate subcompartment. Proper mitochondrial function depends on a process called proteostasis, which ensures that functional proteins are in the right location at the right concentration at the right time. Membrane proteins present unique challenges to the proteostasis network as they must be targeted to the correct membrane and overcome substantial thermodynamic barriers to enter and exit the lipid bilayer, all while avoiding the formation of potentially toxic aggregates in the cytosol. Failures in proteostasis are associated with many neurodegenerative diseases, whereas cancer cells are acutely dependent on robust proteostasis networks to counteract the protein imbalances caused by aneuploidy and dysregulated protein synthesis.