The early onset of disability (at birth through young adulthood) can affect a person's employment outcomes in myriad ways. In addition to the direct effect of disability on employment, early onset of disability likely affects the acquisition of education and job skills (human capital). This reduced "investment" in human capital in turn may reduce the individual's employment and earnings prospects throughout their lifetime. If this is the case, people with early onset of disability may be doubly disadvantaged when it comes to later employment prospects. This study analyzes how early onset of disability (onset prior to age 22) affects employment opportunities both directly and as a result of reduced investment in human capital (education) for a younger cohort (ages 22 to 35) and older cohort (ages 44 to 54). In our young cohort, we find that people with early onset of disability have a lower probability of completing high school and a lower probability of being employed than those without disabilities. Lower employment rates result from both lower levels of high school completion and a direct negative impact of disability on work. In the older cohort, we find the employment of those with disability is lower than those without disability, regardless of age of onset. However, those with early onset of disability have significantly higher employment rates than those with later onset of disability (after age 22). We hypothesize that this is a result of people with onset of disability prior to age 22 either choose careers that can be more easily accommodated than the careers people with later disability onset have, or that people with early onset of disability are more likely to be adept at seeking and using accommodations than those with later disability onset. These results suggest that policies and programs to increase employment of persons with disabilities should focus on ways to increase education levels of those with early onset of disability. They also suggest that return-to-work efforts focused on older cohorts of persons with disabilities may want to separately target programs to those with early onset of disability. Sensitivity Analysis for Definition of Onset is appended. (Contains 24 footnotes and 12 tables.) [Research funded by the Social Security Administration under a grant from the Disability Research Institute at University of Illinois at Urbana-Champaign.]