We compared 24 low-birthweight subjects of an experimental intervention (LBWE), 32 no-treatment controls (LBWC), and 37 normal birthweight (NBW) subjects. The intervention involved 7 hospital sessions and 4 home sessions in which a nurse helped mothers adapt to their LBW babies. At age 7, LBWE scored significantly higher than LBWC on the Kaufman Mental Processing Composite (p less than .001), Sequential (p = .02), and Simultaneous (p = .001) Scales, after statistical adjustments for socioeconomic status. LBWE did not differ from NBW (F less than 1). These results bear out a divergence between the LBWE and LBWC that first became statistically significant at age 3. The findings suggest that the intervention prevented cognitive lags among LBW children, and that long-term follow-ups are needed to evaluate the developmental effects of efforts to overcome major biological and environmental risks.