The composition of executive function (EF) in preschool children was examined using confirmatory factor analysis (CFA). A sample of 129 children between 3 and 5 years of age completed a battery of EF tasks. Using performance indicators of working memory and inhibition similar to previous CFA studies with preschoolers, we replicated a unitary EF factor structure. Next, additional performance indicators were included to distinctly measure working memory, set shifting, and inhibition factors. A two-factor model consisting of working memory and inhibition fit the data better than both a single-factor model and a three-factor model. Findings suggest that the structure of EF in preschoolers that emerges from CFA is influenced by task and performance indicator selection. (Contains 2 figures, 5 tables, and 4 footnotes.)