Theory of Mind (ToM) and Executive Function (EF) have been associated with autism and with attention-deficit hyperactivity disorder (ADHD), and hence might play a role in similar syndromes found following profound early institutional deprivation. In order to examine this possibility the current study included a group of 165 Romanian adoptees, of whom 144 were adopted into the UK from deprived institutional settings before 43 months of age, and a group of 52 within-UK adoptees, all adopted before 6 months of age. Both groups were assessed at 6 and 11 years. The Strange Stories task was used to assess ToM and the Stroop task was used to assess EF, both at age 11. The Romanian adoptees displayed deficits in both ToM and EF compared with the within-UK adoptee group. The degree of deficit was greater for children who had experienced more than 6 months of institutional deprivation. Deficits in both domains (ToM and EF) were associated with each of the three apparently deprivation-specific problems, namely quasi-autism, disinhibited attachment and inattention/overactivity. Statistical analyses indicated a mediating role for both ToM and EF with respect to quasi-autism; possibly a partial mediating role for EF with respect to inattention/overactivity; and probably no mediating role for either ToM or EF in the case of disinhibited attachment. In conclusion, there is evidence for a possible mediating role for ToM and EF in the development of some apparently deprivation-specific difficulties in institution-reared Romanian adoptees, but neither accounts for the overall pattern of deprivation-related difficulties.