Using data on approximately 2,000 low-income welfare recipients in a three-site random-assignment intervention conducted in the early 1990s (the NEWWS), we examine the role of cognitive and non-cognitive factors in moderating experimental impacts of an adult education training program for women who lacked a high school degree or GED at the time of random assignment. Both cognitive and noncognitive skills (in particular, locus of control) moderate treatment impacts. For the sample as a whole, assignment to an education-focused program had a statistically significant (albeit modest) 8 percentage point impact on the probability of degree receipt. For those with low cognitive skills, virtually all of these program impacts were eliminated. However, non-cognitive skills play a substantively important role such that women with high cognitive skills but low non-cognitive skills are only half as likely to earn a degree as their counterparts with high skills of both types. (Contains 4 tables, 2 figures and 8 footnotes.)