Ig-like transcripts (ILTs) encode cell surface receptors expressed on myeloid and lymphoid cells that are structurally and functionally related to killer cell inhibitory receptors. One ILT, designated ILT1, contains a short cytoplasmic domain that lacks sequence motifs implicated in signal transduction. Its function is unknown. Similar short cytoplasmic domains have been observed in activating NK cell receptors and FcalphaR, which transduce stimulatory signals via associated DAP12 and FcepsilonRIgamma proteins, respectively. Here we show that ILT1 receptor is selectively expressed on myeloid cells, functions as an activating receptor, and associates with FcepsilonRIgamma rather than DAP12.