Objective A novel Oral Lichen Planus Symptom Severity Measure was developed as a clinical outcome assessment of the daily symptom experience of patients with oral lichen planus. Methods A literature review and expert input were followed by open-ended concept elicitation interviews with 17 adults with oral lichen planus in the United States and Ireland. Item content was generated, and the interviews continued until input saturation was reached. The final electronic version of the measure was cognitively debriefed in 6 US patients and subsequently translated and linguistically validated in Germany and Denmark. Results Concept elicitation interviews demonstrated content validity and saturation in identifying symptoms and daily activities that generate symptoms in patients with oral lichen planus. The content and electronic daily diary format demonstrated content validity during cognitive debriefing interviews. Linguistic validation of the 7-item Oral Lichen Planus Symptom Severity Measure in Germany and Denmark confirmed the content validity of the German and Danish versions. Conclusions Qualitative research methods generated evidence that the 7-item Oral Lichen Planus Symptom Severity Measure version 1.0 is a well-defined assessment tool to characterize the severity, specificity and variations of symptoms in patients with oral lichen planus.