The Flynn Effect postulates that intelligence is increasing over time. However, as an environment becomes optimal, a plateau occurs when general growth becomes largely determined by genetics. There is evidence that such a plateau is occurring for intelligence in countries with optimal social environments. In the United States, examination of adult Wechsler test scores between normings indicates a reduction of the FSIQ increase such that average FSIQ would plateau about 2024. However, the WAIS-III norming process eliminates many types of subjects with possible brain impairment. This probably raises the average FSIQ level. With an increase of only 1 FSIQ point in 16 years, a plateau in the Flynn Effect would have been reached in 2004.