Research investigating executive function is difficult in two different ways. First, executive function has only recently evolved into its own field of study, and unlike the fields of personality or intelligence, it therefore does not have a wide body of prior research to draw upon. The second difficulty follows from this limited knowledge base. The many different approaches to the study of executive function have given a diverse set of ways to define and operationalize it, leading to numerous contradictions in the literature. This study addresses these contradictions by examining three different theories and four models related to those theories in an effort to understand how each fits the same data set. Models from Miyake and Friedman’s (2012) and Faneros’s (2011) factorial models, Peterson and Posner’s (2012) biological model, and Barkley’s (2012) clinical model are each described and analyzed using confirmatory factor analysis. Additionally, path analysis was used with each model to assess the model’s stability and strength at predicting performance on a complex executive function task. The results indicate Peterson and Posner’s theory provided a model that proved to have the best fit and was the most parsimonious of all the proposed models, χ2 (10, N = 306) = 7.047, p =.72, CFI = 1.000, SRMR = 0.024, BIC = 4692. Each model’s strengths and weakness were explored, and future directions considered.