This dissertation explores the influences on individual decision making in a complex, real world context – the New Zealand wool supply chain. It asks two fundamental questions, first, how do decision makers make decisions in their everyday settings and, second, how is decision making learned and improved through experience and contextual factors. Two contextual aspects of decision making were also examined; these included whether decision making processes varied as a result of uncertainty and risky surroundings, or in cooperative and competitive environments. Further examination included revealing how being a member of a (multi-layered) group influences individual decision making. In-depth qualitative interviewing of sheep farmers, and associated supply chain members in the wool industry was undertaken. Three key decision journeys were explored from both the 'psychological' and the 'social' schools of social psychology in order to give detail on the flow of decision making influences through human systems (whether entities were present, or implied). One of the main aspects of this study was to employ, by analogy, an analysis inspired by the concept of multi-level selection from evolutionary theory as a means of understanding decision making in such a complex, layered system. Other contributions include commentary on the nature of social psychological studies of decision making, suggestions for the expansion of naturalistic decision making to include processes occurring on more than one 'level' of context, the framing of information in the media and the judgment of information sources on the part of experienced and inexperienced farmers, and, the role that globalization may play in driving decision making behaviour.