In this paper, we adopt a Communication as Constitutive of Organizations (CCO) perspective to investigate how organizations implementing Open Strategy initiatives maintain openness and closure in tension by attending to a plurality of voices and their diversity (polyphony), while at the same time speaking in one strategic voice (monophony). Based on the Kiabi case, we explore what we name the voice dilemma by focusing on the ways different stakeholders involved in strategy making manage the co-authoring of strategy through voicing, negotiating, and legitimizing matters of concern. We contribute to extant literature by focusing on the management of polyphony and monophony as a way to embrace the paradox of openness that characterizes Open Strategy. More precisely, we show how some form of closure needs to be nurtured during the opening process (the co-authoring process during which multiple employees are invited to contribute to strategizing). However, we also argue that some form of opening needs to be nurtured during the closure process (the process during which the official authoring/positioning of the organization is finally defined). This study offers a longitudinal case that allows showcasing how the opening and closing strategies evolve over time.