Chapter 1 provides an introduction to evolving complexity theory (ECT) of talent development (TD), a new theory that adopts a relational developmental-systems perspective on how talent is developed and human excellence achieved. A developmental-systems theory has to address the questions of what develops, how it develops, when it takes place, where (i.e., social-historical conditions and cultural contexts) it takes place, with each constraining one’s chance of success. Evolving complexity refers to the nature of TD as encompassing biological, experiential, cognitive, and sociocultural aspects in developmental self-organization, resulting in distinct individuality, of which specific talent achievement is a manifestation. ECT distinguishes itself from other TD models in its emphasis on the primacy of action/interaction, and the nature of TD as adaptation to task affordances and constraints. ECT also views TD as the means to an end of creating a productive, fulfilling life, and there are many niches and pathways to excellence within and across domains.