Relatively little is known regarding mechanisms of environmental exposures in the development of autoimmune disease. However, several environmental agents are implicated in triggering or accelerating systemic autoimmune disease, including mercury, iodine, vinyl chloride, certain pharmaceuticals, and crystalline silica. There is increasing epidemiological evidence supporting the hypothesis that occupational silica exposure is associated with a variety of systemic autoimmune diseases, including scleroderma (SSc), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), glomerulonephritis (GN) and small vessel vasculitis (SVV). However, there have been few mechanistic studies examining silica exposure and autoimmune disease initiation and progression. This review summarizes human epidemiology data linking silica exposure with systemic autoimmune disease, but focuses on possible mechanisms by which silica can lead to the development and progression of autoimmunity.