Within Westminster-based majority parliaments, the presence of minority government runs contrary to the conventional wisdom. Over the last 40 years, however, there has been a steady voting trend away from major parties in many of these parliaments. The complex composition of the Australian Senate after July 2014 reinforces that non-ministerial marginal members continue to be a vital part of the political landscape. This article introduces the concept of the marginal member and examines the potential influence of these members for legislative outcomes and lobbying success. In doing so, the article provides a heuristic through which to identify avenues of policy influence and presents a range of strategies for lobbyists working with marginal members within minority-government contexts.