The innate immune system is characterized by congenital rapidly-activated responses by low-affinity receptors, including cytokine receptors, to gain wide-ranging target recognition. The main players in the innate immune system are classified into 3 different groups; myeloid lineage cells including macrophages, dendritic cells and granulocytes, innate T cells including g d T cells, NKT cells and MAIT (mucosal associated invariant T) cells, and innate lymphoid cells (ILCs). ILCs have been divided into 3 groups based on their cytokine production profiles; group 1 ILC including NK cells and ILC1 produce IFNγ, group 2 ILC (ILC2) produce type 2 cytokines such as IL-4, IL-5, IL-6 and IL-13, and group 3 ILC, including lymphoid tissue inducer (LTi) cells and ILC3s produce IL-17 and IL-22. In this workshop, we would like to discuss the development, signaling pathways, cell-cell interactions and functions of a variety of innate immune cells.