We report herein the results of the cross-cultural adaptation and validation of 2 health related quality of life instruments into the European Spanish language. The Childhood Health Assessment Questionnaire (CHAQ) is a disease specific health instrument that measures functional ability in daily living activities in children with Juvenile Idiopathic Arthritis (JIA). The Child Health Questionnaire (CHQ) is a generic health instrument designed to capture the physical and psychosocial well-being of children independently from an underlying disease. The Spanish CHQ was fully validated with 3 forward and 3 backward translations, while the Spanish CHAQ, already published, was revalidated. A total of 149 subjects were enrolled: 80 patients with JIA (28% systemic arthritis, 34% polyarthritis, 17% extended oligoarthritis, and 21% persistent oligoarthritis) and 69 healthy children. The CHAQ appropriately distinguished healthy subjects from JIA patients, with those classified in the systemic arthritis, polyarthritis and extended oligoarthritis categories having a higher degree of disability and pain, as well as a lower overall well-being than their healthy peers. The CHQ was also able to discriminate healthy subjects from JIA patients, with those allocated in the systemic arthritis, polyarthritis and extended oligoarthritis categories having a lower physical and psychosocial well-being than their healthy counterparts. In conclusion, the European Spanish version of the CHAQ-CHQ is a reliable and valid tool for the functional, physical and psychosocial assessment of children with JIA.