The purpose of the current study was to test the psychometric properties of the Morningness-Eveningness Scale for Children (MESC) to establish normative data, determine cut-off scores for differentiating between morning, intermediate and evening types, and test factorial invariance according to sex and age in a Spanish adolescent population. Additionally, self-reported sleep habits were related to morningness-eveningness (M-E) to study their convergent validity. A sample of 5387 Spanish youth aged 10-16 years old (50% girls) were included in this study. The results revealed that the MESC has acceptable reliability (alpha = .70), good fit to empirical data with a one-dimensional factorial structure, and metric invariance according to sex and age. M-E scores decreased with age, and boys scored higher in M-E compared to girls. Age and sex size effects were moderate and slight, respectively. The relationship between M-E and sleep habits indicated a delayed pattern of sleep-wake habits in evening types compared to morning types. The Spanish version of the MESC possesses good psychometric properties regarding reliability, metric factorial invariance and convergent validity with self-reported sleep habits. (C) 2015 Elsevier Ltd. All rights reserved.