From 5,003 files of adopted children, 65 deprived children, defined as abused and͞or neglected during infancy, were strictly selected with particular reference to two criteria: (i) They were adopted between 4 and 6 years of age, and (ii) they had an IQ <86 (mean ‫؍‬ 77, SD ‫؍‬ 6.3) before adoption. The average IQs of adopted children in lower and higher socioeconomic status (SES) families were 85 (SD ‫؍‬ 17) and 98 (SD ‫؍‬ 14.6), respectively, at adolescence (mean age ‫؍‬ 13.5 years). The results show (i) a significant gain in IQ dependent on the SES of the adoptive families (mean ‫؍‬ 7.7 and mean ‫؍‬ 19.5 IQ points in low and high SES, respectively), (ii) IQs after adoption are significantly correlated with IQs before adoption, and (iii) during adolescence, verbal IQs are significantly lower than performance IQs.

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Failure rates observed (13 +/- 6 percent for school failures, 17 +/- 5 percent for scores below 95 on a collective IQ test) were far below those expected from the social class of birth (55 percent, 51 percent) or observed in a control group (56 +/- 8 percent, 49 +/- 9 percent) but close to those expected from the social class of adoption (15 percent, 15 percent).