BackgroundParents of pre-schoolers diagnosed with Autism Spectrum Disorder (ASD) report increased parenting stress (i.e., stress related to the parent role) and more behaviour problems of the child compared with parents of non-autistic pre-schoolers. Parenting stress and children’s behaviour problems are both associated with parenting behaviours, but have not yet been investigated together. Method42 mothers of autistic and non-autistic pre-schoolers were observed during mother-child interaction and they reported on parenting behaviours, parenting stress, and children’s externalising behaviour problems. Spearman correlations between all variables were calculated for the ASD group and the non-ASD group separately, and Linear Mixed Models were built to investigate whether parenting stress and externalising behaviour problems were similarly associated to parenting behaviours in both groups. ResultsMothers in the ASD group reported more parenting stress and more externalising behaviour problems than mothers in the non-ASD group. In the ASD group only, parenting stress was related to externalising behaviour problems but not to the level of autism characteristics. In both groups, more externalising behaviour problems were associated with more observed negative parenting behaviours (i.e., criticising and ignoring the child), and more parenting stress was associated with less reported autonomy support. ConclusionsOur findings indicate that in the case of possibly problematic parenting behaviours, such as negativity and lack of autonomy support, it is important to investigate associated factors like parenting stress and children’s behaviour problems. An individualised strengths and needs assessment could then offer a tailored intervention to families with an autistic pre-schooler.