The growing ability of the Humanitarian Sector to apply lightweight lean innovation techniques and deliver promising new Pilot programs has not been matched by corresponding capacity to bring these ideas to scale. The initial explanation this shortfall has been the failure of the Pilots to adequately apply techniques such as User Centered Design. This focus ignores deeper more systematic challenges in the way an innovation must be transformed from a fast moving Pilot to a mature solution ready for replication. We've identified the gap between these two very different solutions states as the Missing Middl of innovation. It is characterized by complex solution architecture challenges across multiple domains. This paper describes the nautre of Scale Up challenges in light of the Humanitarian Sector.