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.

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).

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