This book examines the role of extraversion in relation to stress, perceived energy, and health status. In particular, 4 studies are presented along with an extensive literature review linking extraversion to each of these variables. To guide the reader, the sections of the text are categorised along three models of the causal primary hypotheses, specifically that personality, in particular, extraversion, causes or influences behaviour. Based on these models it is speculated that extraversion is a construct distinct from perceived state energy, that perceived energy and extraversion interact with daily stress to impact health status, and that perceived energy mediates the extraversion and stress to health status/stress relationships.