Recent research has studied the link between schooling and income. Evidence indicates the strong relationship found between level of education and lifetime earnings levels. Labor economists have designed studies and measured educational outcomes to differentiate between earnings associated with innate ability and earnings associated with investments in education. A series of studies to control ability using intrafamily measures, including surveys of fathers, sons, brothers, and twins attending an annual convention of twins, helps to identify the relatively robust finding that returns to education average around 10 percent. Other "natural" experiments using time of year of birth and compulsory school attendance laws and draft lottery numbers from the Vietnam War era also shed light on the magnitude of educational effects and support the 10 percent figure. (Appendixes include eight footnotes and three figures.) (YLB)