Background: Healthy development in children is largely influenced by parent-child interactions. However, the parent-child relationship can be affected by several psychosocial risk factors, especially maternal mental health, that undermine its quality and in turn play a negative role in children's psychological health. Objective: The present study therefore examined (a) the associations between maternal self-reported psychopathology and behavioral, emotional, or social functioning in preschool children, and (b) which mechanisms could explain this association. Method: We assessed 63 mother-child dyads. Maternal symptoms of psychopathology were assessed via the Brief Symptom Inventory (BSI), children's behavioral problems with the CBCL. The quality of mother-child interactions was observed during a standardized problem-solving task. Interactions were videotaped and rated by two blind raters. Results: Multiple regression analyses showed that maternal mental strain accounted for 13% of the variance of children's externalizing and 14.5% of internalizing symptoms. Furthermore, the quality of the mother-child interactions also predicted internalizing problems in preschool children. Additionally, results suggest a mediating role of maternal intrusiveness on the association between maternal mental health problems and internalizing but not externalizing symptoms. Children of mothers reporting high levels of mental strain had fewer internalizing problems if their mother presented less intrusiveness during the interaction. Discussion: Consequently, this study adds new insights and understanding of behavioral problems of preschoolers. In order to improve the treatment of preschool children with mental health problems, it is mandatory to reduce maternal psychological strain and to improve the quality of mother-child interactions.