RESUMEN
In Chile, there are no validated instruments for the evaluation of quality of life (QoL) of people with Down syndrome (DS). To analyze construct validity and reliability of the KidsLife-Down scale in Chile to measure QoL in people with DS aged from 4 to 21 years. Families of boys, girls, and young people with DS between 4 and 21 years were invited to participate. The scale was answered by relatives or caregivers. To assess the internal consistency, reliability tests were performed using Cronbach's alpha coefficient. A confirmatory factor analysis was performed. The scale was answered by 531 relatives or caregivers. Cronbach's coefficient was greater than 0.7 in all the items. The confirmatory factor analysis of the scale allowed its validation for clinical use in the Chilean population. "Kids Life Down-Chile" scale has adequate psychometric properties to be used in clinical practice and to help us improve QoL with better support strategies.