This paper was commissioned by the Humanitarian Policy Group (HPG). It is part of a broader HPG study into the role of the private sector in support of humanitarian action. This paper contributes by exploring systematically the new roles companies are playing in humanitarian action. It assesses the forms such engagement is taking, with a particular focus on partnerships, and explores the underlying motivations for engaging in new ways. It also addresses whether new forms of corporate engagement and new donor funding patterns represent potential competition to humanitarian actors, and how this impacts on humanitarian principles. The paper is a product of a scoping exercise to assess the depth and nature of non-commercial and commercial business engagement in humanitarian relief; eight illustrative case studies; and interviews with numerous experts and practitioners conducted over 2006 and early 2007.