A broad comparative framework may offer new insights into factors shaping sex-bias in leadership across mammalian societies, including those of humans. However, despite recent advances in studies of leadership within a comparative framework, the role of ecology in favoring female-biased leadership remains poorly understood. Moreover, traditional definitions of leadership may themselves be gender-biased. We therefore propose a new agenda for assessing the overlooked ways that females exert influence in groups through informal leadership roles and coalition-building within their social networks. This workshop brings together an international team of experts from the biological and social sciences to critically evaluate our understanding of the role of ecology and existing operationalizations of leadership in human and non-human mammalian societies. Specifically, this workshop will focus on the social and ecological factors favoring female leadership in mammalian societies – of humans and non-humans – that vary in size and level of organizational complexity. Other contributions will address the power of female bonds, networks and coalitions, evolutionary bases, historical perspectives and societal implications of female leadership. Through this transdisciplinary lens, the workshop aims to elucidate the diversity of contexts and mechanisms associated with the influence of female leaders on collective behavior.