In the early decades of the century a number of geneticists and psychologists believed that intelligence in the economically advanced nations was in secular decline. Contrary to this expectation, recent data for a number of countries have shown that intelligence has been increasing at rates far greater than hitherto considered probable. A compilation of this data by Flynn for 14 economically advanced nations has shown that intelligence quotient (IQ) rises have generally been within the range of 2-12 IQ points per decade. These recent studies raise several questions, among which are precisely what abilities have been increasing over time; and whether existing data are correct in suggesting that the secular rise in Britain is lower than that in other countries. We report here that in English children there has been an increase over the past 50 years of 12.42 IQ points, averaging 2.48 points per decade. The increase has been in fluid intelligence, the mental power that underlies the acquisition of cognitive skills, rather than in crystallized intelligence, which represents the cognitive skills acquired in a particular culture.