Wnt signaling has been shown to be critical for proper embryonic development as well as growth regulation of certain adult tissues. Defects in Wnt pathways have additionally been associated with a number of human cancers. However, it is only recently that a role for Wnts in the immune system has come to be appreciated. Wnts have now been shown to play significant roles in early stage development of both B and T lineage cells. Current studies suggest that proliferation and/or survival of these cells is associated with activation of the 'canonical' Wnt/beta-catenin pathway. Functional Wnt signaling appears to also occur in end stage B (plasma) cells where both the 'canonical' and the Wnt/RhoA pathways are activated. Herein, we review the current understanding of Wnt signaling in B and T cell development and the potential involvement of Wnt cascades in lymphoid neoplasia.