This study of staff supporting parents with mild intellectual disabilities or borderline intellectual functioning (MID) focused on staff mindset regarding the extent to which parenting skills of parents with MID can change (an incremental mindset) or are static (an entity mindset). Staff mindset was tested as a predictor of two outcome variables: quality of the working alliance and parental waiting time to ask professional support. In addition, mindset was tested as a moderator of associations between parental adaptive functioning and the two outcome variables. A small majority of staff (56%) held a more incremental oriented mindset. A more incremental oriented mindset was associated with a shorter intended waiting time to seek professional support. Staff mindset moderated the association between parental adaptive functioning and working alliance, that is, lower levels of parental adaptive functioning were associated with lower working alliance quality, but the association was less strong when staff held a more incremental oriented mindset.The results of the current study show that staff mindset might be important for the quality of support for parents with MID and for reducing the risks for families where parents have MID. Attention is due to staff mindset in improving support for parents with MID. © 2014 Elsevier Ltd.