Preference PRO has specialized in linguistic validation for over 30 years. The company was founded in Eastern Europe in 1992 by a group of medical doctors with the goal of standardizing translation of medical documents, Quality of Life questionnaires, and patient-reported outcome (PRO) measures to ensure the validity of translated instruments for medical research. The resulting methodology incorporates linguistic research, clinical expertise, and patients’ feedback. In 1999, we collaborated with the ISPOR Quality of Life Special Interest Group (QoL-SIG), to develop guidelines for the translation and cultural adaptation of PRO measures in compliance with FDA regulations. These guidelines have defined the current practices of linguistic validation. For three decades, our company has grown internationally, managing validation projects in over 50 countries. We support all steps of linguistic validation and usability testing for Electronic Clinical Outcome Assessment (eCOA) instruments.