In this chapter we cover advanced topics related to interpretation of the five primary index scores. We conduct a detailed analysis of the cognitive constructs assessed by each of the indexes, how each is related to intelligence through models of cognitive information processing and neuroscience, and how the various cognitive abilities interact with one another and the executive functions in the service of solving problems in real life. We remind psychologists that while an understanding of the abilities being tapped by the index and subtest scores are fundamental to using this test, these scores must also be placed in the larger context of each child and their “world.” There are a huge number of endogenous factors such as genetics and a host of external factors such as culture and education that impact not only the growth and expression of intelligence, but also performance on intelligence tests.