The majority of space plasmas are in a turbulent state, displaying fluctuations and non-linear behaviour at a broad range of scales. As well as being of fundamental interest, this turbulence may have important effects, such as heating of the solar wind and corona, acceleration of energetic particles, and interaction with magnetic reconnection and dynamo. Measurements also suggest the presence of plasma instabilities which may generate fluctuations through linear, quasi-linear or non-linear processes at the same scales as the turbulence. Many aspects of the turbulence and instabilities are not well understood, in particular, the non-linear turbulent cascade and dissipation mechanisms, non-linear instability saturation mechanisms, and the interaction between them. This session will address these questions though discussion of observational, theoretical, numerical, and laboratory work to understand these processes. The session will be relevant for the upcoming Solar Orbiter and Solar Probe Plus missions as well as the proposed THOR mission.