Objective: This study aims at the linguistic and cultural adaptation of the Early ARthritis for Psoriatic Patients (EARP) questionnaire into European Portuguese, for psoriatic patients attending dermatology medical examination. Methods: Firstly, we performed a process of translation and back-translation of the English version of the EARP Questionnaire to European Portuguese, with interim and final harmonization. The resulting Portuguese version was approved by the EARP original author. Secondly, individual interviews were conducted to complete the linguistic and cultural adaptation of the initial translated Portuguese version, with the think-aloud and probe methods. At this stage, we conducted eight interviews, four with rheumatology and dermatology doctors (experts), and four with patients with psoriasis and psoriatic arthritis. Finally, the version resulting from the adaptation process was back-translated from Portuguese to English. Results: Our results showed that EARP Questionnaire’s items are easy to understand and do not raise comprehension concerns in experts or patients. Our findings suggested that items demanding health literacy from patients and that do not include a precise cue to signal the inflammatory nature of the joint pain may lead to confusion while answering, potentially leading to the patient's need for assistance. Conclusion: The Portuguese version of the EARP Questionnaire demonstrated adequate comprehension properties. Our findings support the use of this measure in clinical practice and future research, however, a validation study with Portuguese patients is needed.