Neurodegenerative diseases are a heterogeneous, largely age-related group of disorders, characterised by the progressive degeneration or death of neurons in the central or peripheral nervous system. The prevalence of these diseases is increasing, in part due to the ageing of the population, with a consequent growing economic burden on healthcare systems. Although, in some cases, these diseases can be managed with treatments, current therapies are mostly symptomatic, do not address the underlying cause of the disease and have little or no effect on disease progression. This Special Issue aims to provide an up-to-date overview of the progress made in research into neurodegenerative diseases, from understanding the molecular basis, to establishing more effective diagnostic tools, to developing new therapies. Some papers focus on Alzheimer's disease, Parkinson's disease, motor neuron disease and Huntington's disease. Others address more general aspects of neurodegeneration, ranging from the common mechanisms of cellular damage to the role of dietary effects on the nervous system. Overall, this Special Issue highlights the continuing efforts of the scientific community to unravel the molecular basis of disease onset and progression, to achieve earlier diagnosis, to identify novel therapeutic targets and, ultimately, to develop more effective therapies to counteract the progression of these still fatal diseases.