Validation of design methods is a challenge in design research, as there is a lack of common methodology. This contribution investigates how validation of design methods is currently conducted in order to clarify this issue and identify approaches that might be suitable as best practices. A mixed-methods literature study including the years 2010–2020 is conducted. Systematic mapping structures the identified literature in an overview. The following state-of-the-art review focuses on challenges in validation and on how researchers address them. The overview of 54 identified studies shows a preponderance of non-comparative studies conducted in laboratory environment. Challenges arising in conducting experiments and field studies are caused by a lack of common metrics and established study designs. In success evaluation, the challenge is to objectively measure the effects of method application on the design outcome. Based on the identified examples, possible strategies to overcome the challenges are proposed.
