A latent variable approach was used to (1) examine the relationship between working memory capacity and fluid intelligence, (2) compare the relationship between fluid intelligence and two measures of working memory capacity (complex span and n-back), (3) identify higher-order personality factors and (4) determine the relationship between higher-order personality factors, working memory capacity and fluid intelligence. Confirmatory factor analysis followed by structural equation modeling described the complex span and n-back as highly correlated yet distinct constructs. Consistent with previous research, both measures correlated highly with fluid intelligence. Four higher-order personality factors best modeled the structure of personality. Moreover, these four factors had differential relationship to cognitive constructs. The current research provides a deeper understanding of the relationship between working memory capacity and fluid intelligence, including discrepancies considering the magnitude of the relationship between two types of working memory measures and fluid intelligence, and finally, the influence of a diverse personality structure on working memory capacity and fluid intelligence. Importantly, the study examined these relationships on a broad scale using multiple tasks at a latent level contributing to better understanding of the nature of working memory capacity - fluid intelligence relationship and the influence of personality on higher-order cognition.