Abstract Objective To contain the COVID-19 epidemic preventive measures including social distancing, economic shutdown, and school closures were introduced, carrying risk of mental health burden in adults and children. Although the knowledge base regarding children's response to trauma and adverse events has broadened, descriptions of their mental health during epidemics remain scarce. In particular, the role of family socioeconomic characteristics and parental mental health are poorly understood. Methods We assessed the correlates of children's emotional difficulties and symptoms of hyperactivity/inattention during the COVID-19 lockdown in a French community-based sample. 432 community-based parents (27-46 years, TEMPO cohort) and their children (mean age 6.8 +/- 4.1) were interviewed online. Children's symptoms of emotional difficulties and hyperactivity/inattention were assessed using the parent reported Strengths and Difficulties Questionnaire during the 5th week of home confinement. Family socioeconomic characteristics and parental mental health and substance use were assessed weekly during the first 5 weeks of home confinement. Data were analyzed using multivariate logistic regression models. Results 7.1% of children presented symptoms of emotional difficulties and 24.7% symptoms of hyperactivity/inattention. The presence of psychological difficulties was significantly associated with family characteristics including financial difficulties (OR = 4.3) and parental symptoms of anxiety and depression (OR = 2.5). Children's sleeping difficulties and screen time were statistically significant in bivariate analyses but lost statistical significance in multivariate models. Conclusions Children's emotional and behavioural difficulties are associated with parental mental health and socioeconomic difficulties. In the COVID-19 epidemic, parents and professionals involved in caring for children should pay special attention to mental health needs.