OBJECTIVE: This study assessed the validity and responsiveness of the Spinal Cord Independence Measure (SCIM II) items indoor mobility, mobility for moderate distances, and outdoor mobility. METHODS: . The data of 886 spinal cord injury subjects were derived from the European Multicenter Study for Human Spinal Cord Injury (EM-SCI) and analyzed at 2 weeks and 1, 3, 6, and 12 months after injury. The SCIM II items were compared using the preferred walking speed and the Walking Index for Spinal Cord Injury (WISCI II). The responsiveness to assess differences over time was determined. The analyses were performed for subjects with varying impairment scales according to the American Spinal Injury Association (ASIA). RESULTS: . An initially moderate correlation between walking capacity and the SCIM II mobility items improved to excellent at 6 and 12 months after injury. The correlations were higher for indoor mobility compared with outdoor mobility. These correlations increased in ASIA C, but decreased over time in ASIA D subjects. The SCIM II mobility items showed initially positive responsiveness in ASIA A and B subjects. In ASIA C and D subjects, SCIM II responsiveness was significant within the first 6 months. CONCLUSIONS: . The SCIM II items assess mobility (wheelchair and walking) during daily life. They show good validity and responsiveness, including postdischarge. They can be considered appropriate for evaluating the efficacy of new interventions on ambulatory function. Depending on the severity of the initial lesion and time of assessment, clinically applied walking tests can accurately predict walking performance during daily life.