Uncertainty is high in a world hit by the Covid-19 pandemic, medical emergency, and consequent social and economic disruptions. Yet, variations in levels of acceptance of and “comfortableness” with uncertainty by people, organizations and societies varies globally. Such situations require not only leadership, but also effective leaders. What this is and its ingredients are contested but can be seen as composed of leaders’ thoughts and actions influenced and shaped by key factors stemming from the local operational and situational context, an organization’s particular business culture and their individual competences and skills. We deal with uncertainty in terms of terms and meanings, then its levels and degrees, along with variations in comfortableness with it and its acceptance and how all this might be explained. We then detail some points on leadership, what it is and also effectiveness and requisite skills, end with a conclusion section.