The purpose of this meta-analysis is to examine the nature and magnitude of the relation between complex problem- solving skills (CPS) and intelligence, a topic that has been widely discussed and that has instigated a vast array of partially contradicting findings in the past. Theoretically, researchers have hypothesized the two constructs to be everything from completely separate to identical. Over the course of almost four decades, empirical studies yielded results in support of both arguments. Our meta-analysis of 47 studies containing 60 independent samples and a total sample size of 13,740 participants revealed a substantial correlation of CPS and intelligence with an average effect size of M(g) = .433. In addition, we investigated whether the operationalization of CPS and intelligence moderated this correlation. Whereas there were no significant correlation differences considering the operationalization of intelligence, the approach used to measure CPS moderated the correlation of CPS and intelligence. Especially the most recent approach towards the assessment of CPS yielded the strongest associations between the two constructs. Implications for existing theories and future research are discussed.