This HCUP Statistical Brief presents statistics on 30-day all-cause readmissions among patients aged 1 year and older using the 2010–2016 Nationwide Readmissions Database (NRD). Trends in readmissions by expected payer are provided from 2010 through 2016. Changes in readmission rates between 2010 and 2016 are presented by expected payer. The rate of readmissions and a comparison of costs for the index admission (the initial inpatient stay) and the readmission in 2016 is provided by the type of principal diagnosis. Both the expected payer and the principal diagnosis are determined based on the index admission.