Abstract
Differential susceptibility theory posits that some individuals, with specific characteristics, are more, or less susceptible than others, to both adverse and beneficial environmental influences. It offers a perspective for understanding the directional trajectories across the life course affected by daily context and individual characteristics, in order to identify influential components. The aim of this article is to describe differential susceptibility theory, critically evaluate research findings in which the theory is tested, and consider implications of differential susceptibility theory as a theoretical framework for nursing science. Preterm birth trajectories and outcomes research are used as a lens for this examination.