This chapter provides further understanding of executive functions through discussion of important topics such as the progression of executive function development, its impact on academic and interpersonal learning, its relationship to the diagnosis of mental health problems, and its involvement in brain-behavior relationships. The six vignettes reflect common cases seen in schools, and they highlight the unique developmental and diagnostic considerations that can have an impact on assessment and intervention. Executive function capacities actually begin to develop in early infancy, and aspects of executive control continue to develop possibly throughout a person’s life. The rate of executive function development can change from time to time in a given child. The chapter reviews various issues related to executive function, including the importance of understanding the developmental progression. Although each specific executive function has its own circuit path through the frontal lobes, different regions of the frontal lobes have been identified with different general types of pathways.