This paper presents the Spanish version of the Spence Children Anxiety Scale (SCAS), a rating scale for children and adolescents assessing anxiety disorders as they appear in the DSM-IV. SCAS scores were subjected to confirmatory factor analyses in a sample of 1671 children 10 to 17 years old. Results supported the proposed structure of six interrelated scales. This structure is completely invariant (except for means) in boys and girls and across age groups. Overall, girls scored slightly higher than boys. The relationship of SCAS scores with the child's age was nonexistent or very low and negative. The least frequent anxiety problems among children and adolescents were panic attacks and agoraphobia. Problems that most frequently presented extreme high scores were obsessive-compulsive disorder and social phobia. It is concluded that the Spanish version of the SCAS can confidently be used in the assessment of anxiety disorders in children.