There is evidence for considerable stability of individual differences described by temperament and personality models across the life span (Caspi & Roberts, 2001; Kagan, 2003; Roberts & DelVecchio, 2000). The concept of person-environment transactions offers a fruitful perspective for understanding this stability (Caspi, 1993; Caspi & Roberts, 2001; Smith, Williams, Cyders, & Kelley, 2006; Widiger & Smith, in press).
