g is a highly general capability for processing complex information of any type. This explains its great value in predicting job performance. Complexity is the ma- jor distinction among jobs, which explains why g is more important further up the occupational hierarchy. The predictive validities of g are moderated by the criteria and other predictors considered in selection research, but the resulting gradients of g's effects are systematic. The pattern provides personnel psychologists a road map for how to design better selection batteries. Despite much literature on the meaning and impact of g, there nonetheless remains an aura of mystery about where and why g cognitive tests might be useful in selection. The aura of mystery encourages false beliefs and false hopes about how we might reduce disparate impact in em- ployee selection. It is also used to justify new testing techniques whose major effect, witting or not, is to reduce the validity of selection in the service of racial goals.