Objectives. To linguistically and culturally adapt the Child-OIDP, an Oral Health-Related Quality of Life (OHRQoL) index, into Spanish for use among adolescents, and to validate it by evaluating the psychometric properties of the self-administered version. Study design. Following a forward - backward translation procedure, the English version of the questionnaire was translated by independent translators and the reconciled version was then sent to three experts for assessment. A pilot study was conducted on a sub-sample of 30 adolescents aged between 11 - 12 years to assess their understanding of the questionnaire and its wording. The participants in the main study comprised 425 school children aged from 11 to 14 and pertaining to the oral health survey on school children in Navarre; these children were given a clinical examination and answered a structured questionnaire on oral health self-perception, satisfaction and perceived dental treatment needs. We evaluated the content validity, face validity, criterion validity, internal consistency and reliability. Results. With regard to the face validity, the experts? opinion was that the version was adequate. The pilot study indicated minor changes to the wording to better adapt it for the target population. Regarding criterion and construct validity, the association of the C-OIDP with the self-perception variables gave statistically significant results (p<0.01) in all cases. For the internal consistency analysis, no negative correlations were present in the correlations matrix nor were any of the values too high to become redundant; the majority were statistically significant (p<0.05). Cronbach?s alpha value was 0.68, with corrected item-total values of between 0.20 and 0.56 and with no alpha if-item-deleted values greater than 0.68. The test-retest analysis gave an intraclass correlation coefficient (ICC)=0.98. Conclusion. The Spanish version of the self-administered questionnaire for the C-OIDP for adolescents adequately demonstrated successful psychometric properties and, therefore, is a valid and reliable instrument for measuring the OHRQoL of adolescents.