Dealing with the crises and their consequences requires effective leadership. It has been suggested that the direct influence of leaders on organisational outcomes has been overestimated, which calls for more processual approaches and additional research on the mechanisms that might explain the causal relationship between what leaders do and how what they do affects followers and organisations. Capturing these mechanisms of influence has been challenging, because they are not clearly defined, encompass various elements of a different nature, and are not easily observable. Through an integrative literature review, we disambiguate observable practices from non-observable leadership mechanisms. Four key mechanisms emerge from extant leadership literature: sensegiving, mutual trust, motivating and learning. We contribute to a renewed conceptualisation of leadership as a process, by highlighting the interplay among context, practices, structures and underlying mechanisms. An effective leadership process requires the ability to understand these interactions, especially in the crisis contexts.