A UK literacy intervention – Paired Reading – was replicated in seven Swedish local authorities, with 81 foster children aged 8–12 participating in a 16-week trial. Ability was measured pre/post intervention with age-standardised literacy tests and a short version of the WISC-IV. Results confirm and expand findings from the UK, namely that: almost all foster carers and children completed the programme (attrition 2.4%), average improvement in reading age was 11 months, basically the same as in the UK; younger children (aged 8–9) improved significantly on all four administered standardised reading tests, and on the WISC-IV Vocabulary subtest. Older children (aged 10–12) improved significantly on three of five literacy tests and on the WISC-IV Vocabulary subtest. On the short version of WISC-IV, vocabulary improvements over time reduced the proportion of children who could be classified as having ‘weak cognitive skills’ (IQ <85) from 54% to 36%. This finding is in line with results from other studies, indicating that scores from cognitive tests of pre-teen children in out-of-home care should not be regarded as fixed and can be improved by effective interventions.