Drak2¬-deficient (Drak2-/-) mice are resistant to multiple models of autoimmunity, yet effectively eliminate pathogens and tumors. Thus, DRAK2 is an ideal target to treat autoimmune diseases. However, the mechanisms by which DRAK2 contributes to autoimmunity, particularly type 1 diabetes (T1D), remain unresolved. Our data indicate that DRAK2 contributes to autoimmunity in multiple ways by regulating thymic Treg development and by impacting the sensitivity of conventional T cells to Treg-mediated suppression.