Despite widespread interest in the construct of executive functioning (EF), we currently lack definitive evidence regarding the best measurement model for representing the construct in substantive analyses. The most common practice is to represent EF ability as a reflective latent variable, with child performance on individual EF tasks as observed indicators. The current article critically evaluates the dominant use of reflective latent variable models in the child EF literature and compares them to composite models, a reasonable alternative. We review the literature suggesting that reflective latent variable models may not be the most appropriate representation of the construct of EF. Using preschool (M[subscript age]=48.3 months) and first grade (M[subscript age]=83.5 months) data from the Family Life Project (N=920), we also investigate the implications of measurement model specification for the interpretation of study findings. Children in this sample varied in terms of sex (49% male), race (43% black) and socioeconomic status (76% low-income). Our findings show that the conclusions we draw from 2 substantive analyses differ depending on whether EF is modeled as a reflective latent variable versus a composite variable. We describe the implications of these findings for research on child EF and offer practical recommendations for producers and consumers of developmental research.