Firms can invest in the health of employees through medical examinations, lunches, or avoidance of activities with high accident and death rates. An investment in health that increased productivity to the same extent in many firms would be a general investment and would have the same effect as general training, while an investment in health that increased productivity more in the firms making it would be a specific investment and would have the same effect as specific training. Of course, most investments in health in the United States are made outside firms, in households, hospitals, and medical offices. A full analysis of the effect on earnings of such "outside" investment in health is beyond the scope of this study, but I would like to discuss a relation between on-the-job and "outside" human investments that has received much attention in recent years.