Objective: The aims of the present study were to examine the presence of sluggish cognitive tempo (SCT) symptoms in children; associations of the symptoms with sociodemographic characteristics of the children; and relationships between SCT symptoms and symptoms of ADHD, dyslexia, academic performance, and behavioral problems. Method: We evaluated Catalan schoolchildren aged 7 to 10 years in Barcelona, 2012-2013. Parents filled out the SCT–Child Behavior Checklist (SCT-CBCL), the Strengths and Difficulties Questionnaire (SDQ), and a questionnaire concerning sociodemographic characteristics. Teachers completed the ADHD criteria of Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) (ADHD-DSM-IV), a list of dyslexia symptoms, and evaluated the children’s academic performance. SCT symptoms were studied as a continuous and dichotomous variable. Results: In all, 11% of the children in our sample scored above the clinical cut-off on the SCT-CBCL scale. We observed a higher rate of SCT symptoms in boys, children whose father was unemployed, those whose maternal educational level was lower, children with a high socioeconomic vulnerability index at home, those who reported maternal smoking during pregnancy and current second-hand smoke exposure at home, and children with an ADHD diagnosis. More SCT symptoms were associated with inattention symptoms, symptoms of dyslexia, academic problems, and emotional and peer relationship problems. Conclusion: We observed a higher prevalence of SCT symptoms in our sample than expected in the general population. While girls are less prone to SCT symptoms, some socioeconomic indicators, dyslexia, and inattention symptoms as well as exposure to smoking at home increase the risk of SCT and must be taken into account during assessments.