Despite literature has widely investigated the logics of ideation, at early stages of innovation and product development processes (Bjork and Magnusson, 2009; Boeddrich, 2004; Girotra et al., 2010), very few contributions deal with the very starting point of the ideation process, i.e. the initial theme given to workshops participants. Nevertheless, scholars' works on the nature of stimuli and examples (Smith et al.,1993; Ward et al., 2004) underlined they could generate heterogeneous effects on the efficiency of the ideation stage. Moreover, whereas efficiency criteria for creativity sessions are well known (fluency, flexibility, originality, elaboration), creativity techniques focus on the improvement and monitoring of ideation management: the problem of designing the initial theme is seldom included in the design parameters of creativity sessions, as if it was not considered as an issue in research on creativity management. Yet, one consequence of the above mentioned literature results is that it should be a key efficiency factor: the formulation could play a key role in conditioning cognitive involvement of individuals and managerial goals achievement. This paper focuses on this specific problem of formulating an efficient theme for a creativity session and its implications on cognitive involvement of facilitators and participants, and the achievement of managerial goals of the session. Based on a single case study led through collaborative action research with the French postal service operator, our research analyses the impacts of the formulation in three innovative-oriented creativity workshops the authors have organized and steered from May to October 2013. The three workshops themes were built to experiment the impact of the theme formulation on: 1/ creativity techniques efficiency according traditional criteria and facilitators' cognitive involvement; and 2/ participants' satisfaction assessed through their ability to link the theme, thus the generated ideas, to the company's innovation strategy. The exploratory study confirms that the formulation of the theme has important consequences, both cognitive and managerial. A first set of results suggests two main dimensions to describe the nature and structure of a theme naming: the accuracy level of the formulation and the degree of conceptual tension. A second set of results is about concrete reasoning when designing the theme and implementing in the formulation links to the firm's strategy. A third set of results is about consequences of theme formulation on the way the creativity session is designed and steered. Key dimensions include: 1/ The degree of cognitive implication of facilitators; 2/ The nature of stimuli and idea generation techniques used during the session (generic versus custom-made); 3/ The degree of commitment of the actors (designers of the theme, facilitators and participants) to the organization's strategy, i.e. to what gives value to the output of the creativity session.