Tau protein aggregates are present in a group of disorders, collectively termed the tauopathies. Alzheimer's disease is the most common of those disorders, while frontotemporal dementia is most strongly linked to tau. Now, a map of the proteins that interact with tau and how those interactions differ between normal and disease-associated tau protein could give new clues on how the protein causes damage in neurodegenerative disorders, and on how to treat or prevent that damage.