Cluster headache is a notoriously painful and dramatic disorder. Unlike other pain disorders, which tend to affect women, cluster headache is thought to predominantly affect men. Drawing on ethnography, interviews with headache researchers, and an analysis of the medical literature, this article describes how this epidemiological “fact”—which recent research suggests may be overstated—has become the central clue used by researchers who study cluster headache, fundamentally shaping how they identify and talk about the disorder. Cluster headache presents an extreme case of (...) medicalized masculinity, magnifying the processes of gendering and bringing into relief features of the world whose routine operation we might otherwise overlook. (shrink)