Introduction: The aim of this study was to adapt the Health of the Nation Outcome Scales for people with Learning Disabilities into French (F-HoNOS-LD) and to examine its validity and reliability. Method: Sixty-six adults with intellectual disabilities (ID) admitted to a psychiatric hospital took part in the study. Clinicians used the F-HoNOS-LD and the Aberrant Behavior Checklist (ABC) to test all of them at hospital admission. A subsample (n = 34) was tested with the F-HoNOS-LD a second time at the end of the hospital stay. Results: The French version of the instrument showed evidence of convergent validity with the ABC and very good internal consistency. Repeated measures analyses revealed -- as expected -- a systematic decrease in F-HoNOS-LD scores. Conclusion: Results of this study suggest that the F-HoNOS-LD is a reliable and valid instrument to measure clinical outcomes among French-speaking adults with ID.