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Does lead reduce IQ at the level of g, test specificities, or both? A bare-bones psychometric meta-analysis utilizing the Method of Correlated Vectors was performed on a sample of 16 studies for which subtest-level data could be obtained satisfying stringent inclusion rules. The aggregate correlation across samples between subtest-level estimates of both g loading (g) and the deleterious impact of lead exposure (d) was 0.10 (K = 16, total N = 1935, 80% CI after correction for sampling error = 0.10 to 0.10). So, lead exposure is associated with a slightly positive vector correlation, which is consistent with the results of other studies examining the effects of other neurotoxins on IQ using MCV; this outcome is consistent with two scenarios. The first is that lead exposure may have effects on both g and test specificities owing to systemic effects on many different brain regions. The second is that two antagonistic factors …