We sought to examine the influence of social and clinical factors on risk of progression of chronic kidney disease (CKD) to end-stage renal disease (ESRD) in the urban poor. We studied 15,353 individuals with moderate-to-advanced CKD who received ambulatory care within a large public health system during 1996-2005. The primary outcome was progression to ESRD. Overall, 559 cases of ESRD occurred over a median follow-up of 2.8 years. Among traditional predictors of ESRD, younger age, male sex, non-White race/ethnicity, public health insurance coverage, diabetes, lower kidney function, higher proteinuria, lower hemoglobin level, and lower serum albumin concentration were significantly associated with a higher adjusted ESRD risk (p<.001 for all). There was no significant association between HIV/AIDS (p=.07), viral hepatitis (p=.11), or non-English language (p=.27) and ESRD risk. Our results highlight the importance of addressing traditional risk factors for progressive CKD to reduce the disproportionate burden of ESRD among disadvantaged populations.