Emotion knowledge has attracted scientific interest in recent years due to its relevance to children's adjustment. Although there is some controversy as to its definition and components, the term is often used to describe the set of abilities to process emotional information. We need rigorous tools to assess it in multiple languages and contexts. The Assessment of Children's Emotional Skills-ACES was administered to 255 Spanish 8- to-11-year-old children along with, measures of adjustment and language. The Spanish ACES confirmed its three-factor structure; emotion recognition in faces, behaviours and situational emotional knowledge, and a second-order factor (i.e., overall emotional knowledge). The validity of this Spanish version of ACES was demonstrated in emotion knowledge relating to receptive vocabulary, age, sex and adjustment, with age, language and sex moderating relations between emotion knowledge and adjustment. The Spanish ACES can contribute to a greater understanding of the development of emotion knowledge in Spanish-speaking children; and help evaluate social and emotional intervention programmes.