The emerging sustainability consulting firms are nipping at the heels of the established consultancy giants who are scrambling to find their way in the emergent field of sustainability. The upstarts are challenging many of the established notions of how to add value to their clients' operations. By looking at the business world through what the well-respected sustainability expert Stuart Hart calls 'new sustainability lenses', sustainability consultants are able to make sense of challenges that are baffling their clients. Moreover, they are also beginning to help their clients uncover new value streams, the ultimate goal of good consulting practice.In the papers in this special issue of Greener Management International, sustainability consultants offer some of their perspectives on how to truly create value for their clients.