Canada has pledged to reduce its greenhouse gas (GHG) emissions by 30 percent below 2005 levels by 2030, and has developed a Pan-Canadian Framework on Clean Growth and Climate Change. Canada must seek out every opportunity to reduce GHG emissions while enhancing economic and environmental resilience. Small and medium-sized enterprises (SMEs) offer an untapped opportunity to spur innovation, reduce emissions, create and retain jobs in the clean energy sector, and build local prosperity. This policy brief examines what is already known about sustainability entrepreneurship in the SME sector, and elaborates on the gaps in knowledge that have stymied effective policy making. Better data on the Canadian small business sector is required to provide a deeper understanding of the organizational culture, structure, leadership, and capacity gaps that must be filled to accelerate progress on sustainability.