A number of neurodegenerative disorders were recently coalesced into a group of proteinopathies based on the similarity of molecular mechanisms underlying their pathogenesis. A key step in the development of proteinopathies is a structural change that triggers aggregation of the proteins that are intrinsically prone to form aggregates owing to their physical and chemical properties. The review considers the recent progress in the field of proteinopathies with a special focus on the properties of aggregation-prone proteins, the main stages of the development of molecular pathology, and the role of cell clearance systems in the progression of neurodegeneration. Recent modifications made to the nomenclature of neurodegenerative diseases on the basis of the molecular mechanism of neurodegeneration are also addressed.