Background: The prevalence of albuminuria in the general population is high, but awareness of it is low. Therefore, we sought to develop and validate a self-assessment tool that allows individuals to estimate their probability of having albuminuria. Study Design: Cross-sectional study. Setting & Participants: The population-based Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study for model development and the National Health and Nutrition Examination Survey (NHANES) 1999-2004 for model validation. US adults 45 years or older in the REGARDS Study (n = 19,697) and NHANES 1999-2004 (n = 7,168). Predictor: Candidate items for the self-assessment tool were collected using a combination of interviewer- and self-administered questionnaires. Outcome: Albuminuria was defined as a urinary albumin to urinary creatinine ratio <30 mg/g in spot samples. Results: 8 items were included in the self-assessment tool (age, race, sex, current smoking, self-rated health, and self-reported history of diabetes, hypertension, and stroke). These items provided a C statistic of 0.709 (95% CI, 0.699-0.720) and good model fit (Hosmer-Lemeshow χ2 P = 0.49). In the external validation data set, the C statistic for discriminating individuals with and without albuminuria using the self-assessment tool was 0.714. Using a threshold of <10% probability of albuminuria from the self-assessment tool, 36% of US adults 45 years or older in NHANES 1999-2004 would test positive and be recommended for screening. Sensitivity, specificity, and positive and negative predictive values for albuminuria associated with a probability <10% were 66%, 68%, 23%, and 93%, respectively. Limitations: Repeated urine samples were not available to assess the persistency of albuminuria. Conclusions: 8 self-report items provide good discrimination for the probability of having albuminuria. This tool may encourage individuals with a high probability to request albuminuria screening. © 2011 National Kidney Foundation, Inc.