Background/Context: Although the Flynn effect has been recognized for 60 years and a wide range of factors has been suggested, there is still no agreement on cause. The effect is generally interpreted as a phenomenon involving changes in mental functioning as a consequence of various forms of environmental influence. Purpose: The purpose of the account is to argue that at least part of the change in intergenerational IQ scores is an artifact of the age-based scoring system of IQ tests, together with historical changes in age-grade patterns in school systems. Research Design: This is a logical argument using secondary analysis to illustrate historical change in the demographic patterns at the level of the classroom, together with a survey of psychometric documents and accounts of constructing Otis-type tests to explain the role of age in calculating an IQ. A review of research focuses on whether the IQ measures age or grade and whether age change in a school population can account for an IQ change. Conclusions/Recommendations: It is concluded that because the age-based scoring systems of IQ tests interact with generational changes of age by grade, a Flynn effect should not be interpreted as a massive intergenerational rise in mental functioning unless the two generations match age in grade in the case of school populations, and highest grades achieved in the case of adults.