In assessing a person's disability for the purpose of determining whether or not it prevents him/her from performing specific occupational tasks, a number of facts must be collected and analyzed. These include the worker's general health prior to the event at issue (accident or injury on or due to the job); work conditions preceding and at the time of the event; employer-employee relationship; employee's self-esteem and psychological strength; psychosocial factors outside of the workplace; and social-economic alternatives to remaining productive. A disability assessment must also determine whether the disability is temporary or permanent (chronic). This judgment should be made only at the end of the normally accepted healing period for the injury or when maximum medical improvement has occurred. What causes occupational disability is often more complex than a decrease in physical or mental functioning as a consequence of a particular impairment. Lost time from work may be a function of either medical restrictions that are related to impairment as determined by physicians or dysfunction associated with behavior and social relationships that develop both before and after the accident/injury. Only 10 percent of lost time at work is due only to medically imposed restrictions. All other reasons for lost time are due to employer and employee-controlled impediments for return to work, such as inflexible supervisory decisions, poor injury management practices, breakdowns in communications, and/or employer failures to make reasonable work accommodations. In most cases, the vocational expert, who is trained and experienced in disability analysis, is better prepared than a medical expert to make this judgment. Three case studies are presented. 16 references