The past three decades have witnessed exponential growth in our knowledge of the interactions among the central and peripheral nervous systems and the immune system (Ader, 1981, 2000; Ader, Felten, & Cohen, 1991). In particular, the signals and routes via which psychological and physical stressors lead to endocrine and immune responses have been studied extensively. A detailed picture of an intriguing puzzle has now begun to emerge. Theorists, applied researchers, and professionals are extrapolating these basic findings in order to consider how individual differences in psychological traits and states might be associated with immunity, illness susceptibility, and negative health outcomes (see Cohen & Herbert, 1996; Herbert & Cohen, 1993b; Kemeny & Gruenewald, 1999; Kemeny & Laudenslager, 1999; Kiecolt-Glaser & Glaser, 1995). Quite surprisingly, how such processes affect children's immunity has received scant empirical attention (e.g., Adamson-Macedo, 2000; Boyce et al., 1995; Coe, 1996, 1999). Although the field should be concerned with the ultimate impact of these phenomena for children's health, and additional research with that particular focus seems warranted, the focus of this chapter is on the implications of another leading edge of psychoneuroimmunologic research (e.g., Maier & Watkins, 1998a, b; Maier, Watkins, & Fleshner, 1994). Specifically, accumulated findings have sparked a scientific revolution regarding the direction of effects among the brain, behavior, and immunity (e.g., Blalock, 1994a; Dantzer, 2001).