The cellular environment of the CNS is non-permissive for growth and regeneration. In the retina, transplantation of stem cells has been limited by inefficient survival and integration into existing circuits. In November 2016, as part of the National Eye Institute's Audacious Goals Initiative (AGI), a diverse collection of investigators gathered for a workshop devoted to articulating the gaps in knowledge, barriers to progress, and ideas for new approaches to understanding cellular environments within the retina and how these environments may be manipulated. In doing so, the group identified the areas of (1) retinal and optic nerve glia, (2) microglia and inflammation, and the (3) extracellular matrix (ECM) and retinal vasculature as key to advancing our understanding and manipulation of the retinal microenvironments. We summarize here the findings of the workshop for the broader scientific community.