When James Flynn (1984) first reported that American children and adolescents scored higher on IQ tests than did their peers from an earlier generation, that finding generated few ripples in the literature or in clinical practice. Indeed, how would any other result have made sense? The first sets of data compared children from the mid-1930s with the early 1970s on the Stanford-Binet Form L-M and from the late 1940s with the early 1970s on the Wechsler Intelligence Scale for Children (WISC). The advent of television, the mass media explosion, the increasing awareness of the importance of a stimulating early environment, and other societal changes during the intervening years provided a simple and handy explanation for the 3 points per decade gain that Flynn observed in the United States. Flynn’s (1987) next publication, however, started to rock the empirical and clinical foundations of the nature of intelligence and cognitive development and the psychometric measurement of IQ. The gains in IQ from one generation to the next (which would come to be known as the Flynn effect [FE]) occurred on a worldwide basis, according to data from 14 developed nations, and the 3-point-per-decade American gain paled in comparison with the larger gains in most other nations studied. In fact, gains about twice that large occurred in Japan and in European countries such as Belgium, Germany, and the Netherlands. These gains defied easy explanation (Neisser, 1998). So did the fact that the 3-point-per-decade gain in the United States was not limited to post–World War II societal advances, but continued to occur into the 1980s (Kaufman & Kaufman, 1983), the 1990s (Wechsler, 1991), and the 2000s (Roid, 2003; Wechsler, 2008). FE has apparently stopped, and even reversed, in some Scandinavian countries (Teasdale & Owen, 2008), but it has remained a virtual constant gain for children and adults in the United States for the past eight decades. Researchers differ on why the FE occurs. Some claim that genetics is the key variable (Rodgers & Wanstrom, 2007), though most stress environmental factors such as nutrition (Colom, LluisFont, & Andres-Pueyo, 2005), education (Teasdale & Owen, 2005), or improvement in public health (Steen, 2009). Flynn (2007, 2009), in What Is Intelligence?, explains the effect named after him in terms of a societal shift from concrete to abstract thinking, whereas other scholars and researchers maintain that the so-called effect is nothing more than an artifact of statistical or methodological origin (Beaujean & Osterlind, 2008; Rodgers, 1998). And, in fact, the dispute about the scientific validity of the FE has entered the U.S. courtrooms in a big way as a burgeoning array of law cases asks whether the FE should be considered when sentencing low-functioning criminals convicted of a capital crime. Ever since the Supreme Court’s decision in Atkins v. Virginia (2002), which stipulated that a criminal who is mentally retarded cannot be executed,