Background: ADHD is a debilitating disorder with symptoms often appearing in early childhood. To facilitate early identification, developmentally appropriate and validated assessment tools for the preschool-age are needed. Aims: The current study aims to examine the psychometric properties of the ADHD Rating Scale (RS)-IV Preschool Version (-P) in a Danish community sample and provide national standardisation data. Methods and procedures: Parents (n = 916) and kindergarten teachers (n = 275) of preschool children, aged 3–5 years, completed the ADHD RS-IV-P. Outcomes and results: Confirmatory factor analysis indicated that a three-factor model (inattention, hyperactivity, and impulsivity) best fit the data regardless of rater. Scales generally showed acceptable internal consistency, test-retest reliability, inter-rater reliability, and criterion validity. Boys received higher ratings on the ADHD RS-IV-P than girls and younger preschool children were rated as more inattentive than older preschool children. Conclusions and implications: Our findings support the reliability and validity of the ADHD RS-IV-P and a three-factor model of ADHD. However, high factor correlations and similarity in model fit suggest that more research is needed to clarify the organisation of ADHD symptoms in preschool children. Furthermore, the external validity of separate ADHD dimensions at this age should be examined.