Innate lymphoid cells (ILCs) are tissue-resident lymphocytes that promote immunity to pathogens at mucosal barriers, but the mechanisms regulating their development within tissues remain poorly understood. In this issue of Immunity, Oherle et al. identify a niche in the neonatal airway where stromal cell-derived insulin-like growth factor 1 (IGF1) supports the proliferation of ILC precursors and protects from infection.
