Paying research participants is a widespread, long-standing, ethically acceptable, and perennially fraught practice. Although data are limited, payment is offered to participants in many research studies with amounts ranging from a few dollars to several thousands of dollars. Payment can facilitate recruitment to clinical trials and enables research participation for persons in a variety of studies by replacing some of their otherwise lost wages or reimbursing them for expenditures. Payment may be essential to motivate and compensate healthy phase 1 trial participants, as it is usually their primary reason for joining these trials. IRBs, sometimes uncomfortable with payment, generally keep amounts of payment low in an effort to comply with ethical and regulatory directives to minimize the possibility of undue inducement and coercion. Commentators continue to justify payment across many types of studies and have called for paying higher amounts in order to mitigate exploitation or make research participation fairer.