Background Children placed in care because of abuse or neglect can display a range of challenging behaviours that can be difficult for foster carers to manage. While much is known about the prevalence of behavioural disorders among children in care, little quantitative information exists about which behaviours are problematic for carers. Method Two hundred and one foster carers of children aged 4–12 were asked to rate a range of potentially problematic behaviours via online survey. Items were drawn from existing clinical measures, a review of the practice literature, and focus group consultation. Results Principal component analysis yielded four distinct profiles of behaviours that carers identified as problematic. The first component reflected cognitive difficulties (e.g., executive functioning, language, and memory problems). Component 2 comprised sexual or otherwise risky behaviours (e.g., drug or alcohol use). Component 3 contained behaviours of an aggressive, controlling, and violent nature (e.g., enjoying upsetting others). Component 4 contained anxiety‐based behaviours (e.g., obsessive compulsive behaviour). Collectively, these four factors accounted for almost 60% of the variance. Conclusions Four discrete profiles of problem behaviours were identified. These distinct groups of behaviour serve as a focus for targeting supports that may ultimately help enhance foster placement stability.