Emotional lability (EL) is frequent in school-aged children with attention deficit hyperactivity disorder (ADHD) and is associated with more frequent comorbidities and more severe impairment. However, little research has investigated the association between EL, ADHD and comorbid symptoms in preschoolers. This study assessed dimensional EL in preschoolers and its link with ADHD symptoms (e.g. hyperactivity-impulsivity and inattention) and behavioural and emotional problems (e.g. aggression and anxiety).