Performing Leadership 'In-Between' Earth and Sky

International audience; This research aims to understand how leaders with different expertise perform distributed leadership through their discursive acts. Relying on Searle's (1976) Speech Acts Theory and its derivative model of organizing through communication as developed by Cooren (2001) and Fairhurst (2007; Cooren & Fairhurst, 2004), we conduct an in-depth analysis of the interactions (through emails and phone calls) between the forecasters (the " earth ") and the team leaders (the " sky ") during the summit attempts of two commercial expeditions: one to Broad Peak and one to Mt. Everest via the Northern Ridge. Our research contributes to the understanding of the enactment of distributed leadership in three ways. Firstly, it provides an unprecedented description of the pattern of speech acts through which leaders perform two configurations of distributed leadership, namely coordinated leadership and collaborated leadership (Spillane, 2006). Secondly, the process analysis conducted on the forecaster and team leader interactions shows that these two leadership configurations do not completely substitute for each other, contrary to what previous studies in education have argued, but can coexist during the same expedition. Thirdly, our research contributes to a socio-constructionist perspective on leadership in showing how, while confronted with similar physical, technological, and socioeconomic conditions and demands, the team leaders and the forecasters enact noticeably different leadership configurations. ! Although, since the late 1980s, 8000m summits have attracted an increasing number of commercial expeditions, the 1996 Everest tragedy reminds us that mountaineering at high altitudes remains highly risky (Krakauer, 1997; Kayes, 2004; Tempest, Starkey, & Ennew, 2007). Making sense of and adapting to a hostile, complex, and fast-changing environment requires not only that the individual be in very good physical condition and possess a high level of technical expertise and experience, but also have the capacity to adapt to, if not anticipate, a hostile, ever-changing environment; a capacity that becomes all the more vulnerable as physical, emotional, and cognitive abilities become severely altered due to fatigue, cold, and lack of oxygen (Elmes & Frame, 2008). ! Since the 1996 tragedy, mountaineering has dramatically evolved. To increase their probability of success in summit attempts, and thus the commercial attractiveness of their business, team leaders do not hesitate to use the latest communication technologies (i.e., usually the internet at Base Camp, and mobile and sat phones at higher altitudes) and weather forecasts. Commercial expeditions, in particular, are now systematically assisted by professional forecasters – located worldwide – who send them daily updated weather forecasts that detail the various ascent parameters. Temperature, humidity, wind, and risks of snowfall and storms are estimated for the next few hours and days at different altitudes and for the particular slope of the mountain where the team is