Increasing attention is being paid towards the potential of social innovation (SI) in responding to society’s greatest challenges. While measures have been taken to support the flourishing of these innovations, they have thus far been made on ideal models of development, misaligned with what occurs in reality. This has led to the creation of supporting infrastructures that fail to respond to the real needs of social innovators. The article seeks to provide a picture of the real SI development process through a case-based discussion coming from the results of the SIMPACT European research project. The article will also present areas of improvement and reflection, on which to develop an evidence-based model of SI development. Moreover, it will connect SIs with local conditions that determine their development, suggesting that their growth and diffusion are primarily based on the adaptation to the context rather than on the scaling up mechanisms that characterize for-profits. The article argues that this leads to the necessity for social innovators to find a difficult balance among contradictory needs, and to develop peculiar typologies of business models to make their innovations sustainable.