AITANA researchers have developed a brief questionnaire to assess mood in children. The Brief Mood and Feelings Questionnaire (SMFQ) is one of the few well-established measures for assessing childhood depression. The paper, published in Psicothema, evaluates the psychometric properties and explores the differential item functioning (DIF) of the SMFQ in a community sample of Spanish children. The results of the study conclude that the SMFQ has good internal consistency. The test-retest analysis confirms its temporal stability. The SMFQ is a useful instrument for clinicians who need to assess the severity of depressive symptoms. The questionnaire is brief, reliable, and valid for the assessment of depressive symptoms in Spanish children.