When a debt is seriously delinquent and the creditor sells the debt or refers the debt either to a collection agency or to an internal collection department, the collector or creditor can separately report the account to one or more of the three largest nationwide consumer reporting agencies (NCRAs) as an account in collections. The presence of a collections tradeline can have a negative impact on a consumer's credit score. There are currently an estimated 220 million consumers with a credit report at one or more of the NCRAs. Collections tradelines affect the reports of nearly one out of three of these consumers. Consumers are far more likely to dispute the accuracy of these tradelines than of other information contained on their credit reports.Roughly half of all collections tradelines that appear on credit reports are reported by debt collectors seeking to collect on medical bills claimed to be owed to hospitals and other medical providers. These medical debt collections tradelines affect the credit reports of nearly one-fifth of all consumers in the credit reporting system.This paper describes characteristics of the medical and non-medical collections tradelines on consumers' credit reports and the processes by which they appear and disappear. It draws on analysis of data contained in the Consumer Financial Protection Bureau's (CFPB) ConsumerCredit Panel (CCP); consumer complaints to the CFPB about collections; and interviews with debt collection agencies, healthcare providers, and other observers of the healthcare billing and payment processes. The CFPB has not sought to verify original research introduced in this paper through its supervisory authorities. The paper does not draw upon supervisory information the CFPB has learned through examinations it has conducted, and does not make conclusions about whether any specific market participants are in compliance with particular statutes or rules pertaining to consumer reporting.