This study aimed to replicate and extend the pilot findings of Cassidy et al. (2011) which found that teaching children to derive various relations among stimuli leads to increases in the full scale IQ scores of both typically developing children and those with educational and learning difficulties. In Experiment 1, fifteen 11–12 year old children were exposed over several months to an intensive training intervention to improve their understanding of the relations Same, Opposite and More and Less. Significant increases in full scale IQ of around one standard deviation were recorded for each child. In Experiment 2, the same intervention was delivered to thirty 15–17 year old children. Significant increases in verbal and Numerical Reasoning were recorded for almost every child. These findings corroborate the idea that relational skills may underlie many forms of general cognitive ability.