This paper presents a field study of decision-making processes in management teams in two organizations. It reviews existing literature on managerial knowledge structures and decision-making, and identifies methodological and conceptual limitations with these approaches. The authors then develop interpretive case studies of two management teams, which focus on the articulated and social methods used to make decisions. They found that both organizations used rules of thumb or heuristic reasoning in their decision-making, that these rules of thumb functioned as headlines of deeper organizational narratives, and that these narratives were grounded in emotional as well as purely rational considerations. We suggest that the term “guiding principle ” usefully integrates our three findings into a descriptive concept that may be further explored in future research of both a descriptive and prescriptive nature.