A family of beta-galactosides-binding proteins, called galectins, have recently emerged as novel molecules with immunoregulatory functions. These proteins are expressed in both inflammatory and non-inflammatory cells including monocytes, macrophages, dendritic cells, mast cells, and B and T cells, giving a broad spectrum of involvement in the immune response. Galectins are uniquely capable of acting both intracellularly and extracellularly, affecting such processes as cell adhesion, signaling, proliferation, differentiation, and apoptosis. Different members of this family have been shown to modulate several pathological processes such as allergic reactions, autoimmunity, and tumor invasion. Therefore, understanding the role of galectins in achieving appropriate proliferative and effector responses to antigens will yield important insights to autoimmune diseases and delineate novel strategies for disease intervention.