Introduction Outdoor leaders take people into the outdoors in a myriad of ways. Included are activities such as rock-climbing, kayaking and mountain biking, through diverse domains such as outdoor education, adventure tourism, and club trips. Much of the learning and welfare of group members are in the leader's hands. There is widespread agreement that outdoor programme implementation relies on effective decision making (DM) (Martin, Cashel, Wagstaff & Breunig, 2006; Shooter & Furman, 2011). It is well recognised that the outdoors is a complex and dynamic decision-making environment (Galloway, 2002; Martin, Schmid & Parker, 2009; Tozer, Fazey & Fazey, 2007). The natural environment has intrinsic elements of risk and uncontrolled variables presented by elements such as weather, height, water and speed (New Zealand Department of Labour, 2010). Adding to this complexity is the uniqueness of individuals and the dynamics of groups. Decision circumstances for outdoor leaders vary greatly, with some situations pressured and changeable and others stable and consistent. The dynamic interactions between and among participants, leaders and the environment means that leaders of outdoor activities make countless decisions during an excursion. Examples of outdoor decisions include: (a) place (e.g., where to camp); (b) time (e.g., when to stop for lunch); (c) the needs of individuals (e.g., comfort, safety); and (d) the group process (e.g., is everyone happy). Depending on context, these could be simple or complex decision situations that affect the quality of an adventure experience and the safety of participants (e.g., to cross a river or not, and if so, where, how and when). Consequently, the importance of leader decisions varies from inconsequential to paramount. Drury, Bonney, Berman and Wagstaff (2005) proposed a classification of decisions on a continuum from simple to complex (see also Martin et al, 2006). Here, decisions could be classified depending on a combination of contextual factors including degrees of challenge, uncertainty, predictability of outcome, time pressure, threat, emotionality and situational understanding. Consideration of these arrays appears in several text books (see Drury et al., 2005; Martin et al., 2006; Priest & Gass, 2005). Some empirical research has been conducted to explore different outdoor decision situations. These include: outdoor pursuits leaders (Beare & Lynch, 2005); outdoor education leaders (Boyes & O'Hare, 2003); medical decision making by Outward Bound staff (Galloway, 2007); and outdoor leaders on a Wilderness Education Association course (Martin et al., 2009). Their decision problems include emergency situations such as hypothermia, a lost person, and a spinal injury, as well as whether to cross an alpine pass and a river. Also included are decisions about extending a cross country ski trip to increase the level of challenge. Despite the universality of decisions, researchers have yet to develop a taxonomy of outdoor leadership decisions based on empirical evidence. A deeper understanding would be useful as a basis for understanding more about how different contexts and levels of complexity influence decision processes. The implications of this approach may be useful to inform the education of new and existing leaders and contribute to better practice. The present research explores the range of decisions made by six highly experienced outdoor leaders and presents their data in taxonomies. Some of their key decisions are then explored through the lens of Naturalistic Decision Making (NDM). Naturalistic decision making Hitherto, a modest amount of empirical research investigates outdoor leader decision making and a comprehensive understanding has yet to be agreed upon (Furman, Shooter & Schumann, 2010). Some researchers have focussed on classical DM models where multiple options for action are generated, whereby in a rational, comparative process, the best perceived solution is chosen and implemented (e. …