Three modifications devised to make the Sickness Impact Profile more sensitive to head injury are evaluated in 202 head-injured and 132 general trauma patients 1 month and 12 months after injury. The modifications consist of adding items, deleting nonapplicable items, and reweighting areas of function. Each of the modifications, and especially all three combined, slightly but significantly improve discrimination of head-injured and comparison subjects and increase correlations with neurologic and neuropsychologic severity indexes. These slight improvements occur more often at 12 months than at 1 month and among those without rather than with pre-existing conditions. No improvements are found in the ability to classify patients into subgroups. The modifications fail to make improvements sufficiently large or consistent to provide a practical advantage over the SIP. The standard SIP provides a reasonable measure of psychosocial functioning following head injury. It relates to head injury and other system injury severity and reflects recovery with time. The SIP score relates to emotional functioning even after injury severity has been taken into account. Until other factors, such as emotional status and responses style, are better controlled, little benefit is likely to be obtained from creating disease-specific psychosocial measures.