Uncertainty is an unavoidable dimension of organizational life, and it is also challenging even for the most competent managers (Pich, Loch, & Meyer, 2002). This thesis examined middle managers' uncertainty responses during the formulation and implementation of the strategy process in three studies.The first study was qualitative and intended to expose the sources of uncertainty, managerial responses, and variables, which are essential for middle managers to cope with uncertainty in the strategy process. Study 1, involving interviews with 22 middle managers in civilian and military organizations, resulted in six sources, including a new classification--International instability and disasters--and five different responses: Collaborative responses, Emotional responses, Cognitive responses, Value-based responses, and Bureaucratic responses. In the second study, we conducted a Multidimensional scaling technique (N=70) to create a taxonomy of perception of managerial uncertainty responses in order to understand the nature of uncertainty in any organization and to help to build new theories. Results indicated six clusters: Protection by Support, Protection by Structure, Protection by Scapegoats, Certainty of Change, Development by Debate, and Development by Change. In the third study, we examined the effects of individual responses to uncertainty and organizational factors on managerial responses using quantitative analysis (N=310). The results showed that organizational-level knowledge sharing has positive effects on managers' desire of change. This study added a new source of uncertainty and five different managerial responses to uncertainty, and revealed that individual-level cognitive uncertainty and desire of change result in bureaucratic and collaborative responses. Additionally, we contend that managers respond to uncertainty v variously, from suppressing to collaboration, either to protect themselves or to act towards a constructive change in the organizations.