AbstractAimEarly detection of child developmental and parenting problems is important for timely prevention. The SPARK36 (Structured Problem Analysis of Raising Kids aged 36 months) is a novel broad‐scope structured interview guide aimed at assessing parenting concerns and needs for support for child developmental and parenting problems, using the parental and professional's (Youth Health Care nurses) perspective. The applicability of the SPARK36 in practice was already demonstrated. Our aim was to evaluate its known groups validity.Desing/MethodsSPARK36 data were collected in a cross‐sectional study in 2020–2021. The known groups validity was assessed by testing two hypotheses: the SPARK36 risk assessment shows a higher risk of parenting and child developmental problems in children (1) from parents with a lower socioeconomic status and (2) from families with ≥4 risk factors for child maltreatment. To test the hypotheses, Fisher's exact tests were applied.ResultsIn total, 29 Youth Health Care nurses from four School Health Services performed SPARK36‐led consultations with 599 parent–child pairs to assess the risk for child developmental and parenting problems. Both hypotheses were accepted at a significant p level.ConclusionThe results of the known groups validity support the hypothesis that the SPARK36 risk assessment for child developmental and parenting problems is carried out in a valid way. Future research is needed to assess other aspects of the validity and reliability of the SPARK36.ImpactThis is a first step in validating the instrument for use during a nurse‐led consultation with parents of 3‐year‐olds in Flemish School Health Services. Thereby, SPARK36 supports the nurses in accomplishing their assignment, making a risk assessment, and contributes to quality of care.Patient or Public ContributionThis study aimed to evaluate the known groups validity of the SPARK36. Therefore, it was not conducted using input from the public or the patient population.