Multiple studies have documented significant IQ gains over time, a phenomenon labeled the Flynn effect. Data from 20 industrialized nations show massive IQ gains over time, most notably in culturally reduced tests like the Raven's Progressive Matrices. To our knowledge, however, this is the first study to document the Flynn effect in a rural area of a developing country. Data for this project were collected during two large studies in Embu, Kenya, in 1984 and 1998. Results strongly support a Flynn effect over this 14-year period, with the most significant gains found in Raven's matrices. Previously hypothesized explanations (e.g., improved nutrition; increased environmental complexity; and family, parental, school, and methodological factors) for the Flynn effect are evaluated for their relevance in this community, and other potential factors are reviewed. The hypotheses that resonate best with our findings are those related to parents' literacy, family structure, and children's nutrition and health.
