Aim: The aim of this study was to develop and validate according to psychometric standards a self-administered instrument to measure the students' self-perceptions of the undergraduate clinical dental environment (DECLEI). Materials and methods:The initial questionnaire was developed using feedback from dental students, experts' opinion and an extensive literature review. Critical incident technique (CIT) analysis was used to generate items and identify domains. Thirty clinical dental students participated in a pilot validation that generated a 67-item questionnaire. To develop a shorter and more practical version of the instrument, DECLEI-67 was distributed to 153 clinical students at the University of Athens and its English version to 51 students from various dental schools, attending the 2012 European Dental Students Association meeting. This final procedure aimed to select items, identify subscales and measure internal consistency and discriminant validity.Results: A total of 202 students returned the questionnaires (response rate 99%). The final instrument included 24 items divided into three subscales: (i) organisation and learning opportunities, (ii) professionalism and communication and (iii) satisfaction and commitment to the dental studies. Cronbach's a for the total questionnaire was 0.89. The interscale correlations ranged from 0.39 to 0.48. The instrument identified differences related to school of origin, age and duration of clinical experience. An interpretation of the scores (range 0-100) has been proposed. Conclusions:The 24-item DECLEI seemed to be a practical and valid instrument to measure a dental school's undergraduate clinical learning environment.