The family of innate lymphoid cells (ILCs) comprises of natural killer (NK) cells, Rorγt-dependent ILCs (lymphoid tissue inducer (LTi) cells, ILC22, and ILC17), and type 2 ILCs. Apart from a common requirement for inhibitor of DNA binding 2 (Id2) expression and common γ-chain (γc) signaling, the differentiation of ILC populations is regulated by distinct transcription factors. ILCs play fundamental roles in processes such as cytotoxicity, lymphoid organogenesis, intestinal homeostasis, immunity against infections, and wound healing. However, the dysregulation of ILCs has been implicated in autoimmune and inflammatory diseases. Here, we will review the recent advances in ILC development and their roles in immunity and disease, with a primary focus on type 2 ILCs.