BackgroundGait impairment is one of the main causes of disability in people with multiple sclerosis. The Gait Assessment and Intervention Tool is an observational gait scale that assesses kinematic parameters using video recordings.ObjectiveTo study intra‐ and interrater reliability and the minimal detectable change of the Gait Assessment and Intervention Tool in individuals with multiple sclerosis.DesignObservational study.SettingMultiple Sclerosis Foundation.ParticipantsThirty‐five participants with multiple sclerosis were assessed (12 men, 23 women; 47.7 ± 11 y; Expanded Disability Status Scale = 4.32 ± 1.4).InterventionsNot applicable.Main Outcome MeasurementsIntra‐ and interrater reliability of the Gait Assessment and Intervention Tool was assessed for each limb using the Intraclass Correlation Coefficient. In addition, the minimal detectable change was calculated.ResultsThe Intraclass Correlation Coefficient for the intrarater reliability was found to be excellent for the total score both for the right side (.91; 95% confidence interval 95% CI .85‐.95) and the left side (.93; 95% CI .88‐.96). The intraclass correlation coefficient for the interrater reliability was .91 (95% CI .85‐.95) for the right side, and .93 (95% CI .88‐.96) for the left side. The minimal detectable change for the intrarater reliability was 1.19 points for the right side and .77 for the left side.ConclusionsThe Gait Assessment and Intervention Tool exhibits excellent intra‐ and interrater reliability and a small minimal detectable change for people with multiple sclerosis.