Preparing military strategic leaders and crisis managers for work related to increasing competence and efficiency within their own organization is a complex task. Diversity in organizations is not easy to obtain but still necessary to increase competence and efficiency, not least in military organizations preparing for unforeseen situations. This study rests on two premises: that diversity is essential for handling unforeseen situations, and that a common framework for diversity across organizations is needed to develop inter-professional efficiency. The article aims to discuss the concept of diversity and what importance the nature of diversity can have in preparing military leaders. The term is analysed in accordance with a semantic view of theories and theory construction. The key point is to perceive diversity as a phenomenon consisting of many underlying and interdependent variables, which together constitute different degrees of diversity. Aligning this theoretical analysis with practical work, it is important to identify the organization’s current plans for preparedness and its future need for diversity, including what can limit or hinder the development and implementation of its diversity policy. Our study identifies both potential and hindrances found in the Norwegian Armed Forces as an example. Based on this foundation, we introduce a new strategic model which may support leaders both within and across organizations in their work on diversity development. Based on our theoretical and empirical studies, we also introduce a definition of diversity.