Parental capacity is one of the main aspects assessed by social workers as part of child protection investigations. The aim of this study is to explore the social workers' perceptions of assessing the parental capacity of parents with intellectual disabilities in child protection investigations. Four focus group interviews were conducted with twelve social workers in May-October 2021. Data were analysed using an inductive, conventional qualitative content analysis. One overarching theme, "Parental capacity in relation to the child's needs was assessed, not disability of parents" was created. Three main categories and ten sub-categories were identified exploring the social workers' perceptions of assessing parental capacity. The study shows that social workers perceive the assessment of parental capacity in parents with intellectual disabilities as demanding and complex, in which the assessment of what is good enough is perceived as the most difficult task.