A variety of inflammatory signals can act on myeloid progenitor cells or monocytes to induce differentiation into specialized monocyte-derived populations. Signals can act in a direct (e.g. Toll-like receptors) fashion or through indirect mechanisms (e.g. cytokines) to promote these cell fates. Different combinations of markers and gene expression patterns allow for the identification of monocyte-derived cell populations. TLR, Toll-like receptor; Hh colitis, Helicobater hepaticus-induced colitis; CHIKV, chikungunya virus; T. gondii, Toxoplasma gondii; MDP, Monocyte-DC Progenitor; GMP, Granulocyte Macrophage Progenitor; SatM, segregated-nucleus-containing atypical monocyte; iHPC, inflammatory hemophagocyte; moDC, monocyte-derived dendritic cell.