Dendritic cells (DC) take up antigen from the periphery and migrate to the lymphoid organs where they present the processed antigens to T cells. The propensity of DC to migrate changes during DC maturation and is probably dependent on alterations in the expression of chemokine receptors on the surface of DC. Secondary lymphoid tissue chemokine (SLC), a recently discovered chemokine for naı̈ve T cells, is primarily expressed in secondary lymphoid organs and may be important for colocalizing T cells with other cell types important for T-cell activation. We show here that SLC is a potent chemokine for mature DC but does not act on immature DC. SLC also induced calcium mobilization specifically in mature DC. SLC and Epstein-Barr virus–induced molecule 1 ligand chemokine completely cross-desensitized the calcium response of each other, indicating that they share similar signaling pathways in DC. The finding that SLC is a potent chemokine for DC as well as naı̈ve T cells suggests that it plays a role in colocalizing these two cell types leading to cognate T-cell activation.