Selecting appropriate outcome measures in spinal cord injury clinical trials that aim to improve spinal cord function is a challenging task. Proving that an intervention has the intended effect on neurological functioning is insufficient. Any improvement must be shown to be clinically significant-that is, makes a change in the life of the person. Rehabilitation, which seeks to maximize function despite residual impairments, complicates this task. Small improvements in function due to a spinal cord intervention may be masked by improvements in function due to rehabilitation, particularly in the initial rehabilitation phase of care. Understanding outcome domains in models of disablement will facilitate selection or development of assessment tools appropriate for the trial in question. This article describes an expanded World Health Organization model of functioning that defines the domains of Impairment, Capability/Functional Limitation, and Activity, as well as the subdomains of Capacity and Performance, and gives examples of measurement instruments in use or under development in each domain.