The neural circuitry underlying innate fear is thought to be distinct from the circuits that mediate conditioned fear, but is poorly understood. Yang et al. show that, in mice, the laterodorsal tegmentum (LDT) is activated by a TMT, a predator odorant that induces an innate fear response. Optogenetic stimulation of two different populations of LDT GABAergic neurons had opposing effects on the fear response: stimulation of parvalbumin-expressing interneurons induced fear-like responses, whereas stimulation of somatostatin-expressing interneurons attenuated TMT-induced fear responses. The authors further demonstrate that glutamatergic input from the lateral habenula drives LDT activity to mediate the fear response.