Sustainability and sustainable development is slowly gathering momentum in public discourse, and greater attention and reverence in academic research. While there still appears to be no consensus defining sustainability, which has lead to hampered discussion, this should not impede nor hinder a greater call for dialogue of how to ultimately change the world, and for the global economy to consider what type of individual will address environmental and social issues simultaneously. We consider ‘traditional’ entrepreneurship still necessary and vital to the continuing development of disruptive innovation and market change, however, a new breed of entrepreneur must now achieve greater focus. A sustainable shift in societies development is required to guarantee a capacity to endure. Sustainable development is critical to not only the environments long-term well-being, but also a necessity to curve the ultimate slow demise of the human race. Economic responsibly toward the environment and society is imperative. Sustainable development meets at the confluence of three constituent parts - environmental sustainability, economic sustainability and socio-political sustainability, the foundations to an emerging new field of entrepreneurship - Sustainable Entrepreneurship.Sustainable Entrepreneurs enact a holistic approach to a venture start-up that embeds environmental, economic and social sustainability dimensions. Sustainable Entrepreneurs have received insufficient attention by the media, policy makers and have failed to grab the attention of academics to test theory in an exploratory cross-case analysis approach. Previous research has mainly been conceptual and theoretical. Literature is lacking practical insights into how entrepreneurs conduct sustainable entrepreneurial initiatives and whether such definitions hold true. A cross-case analysis of five entrepreneurs operating in the renewable energy industry is conducted, evaluating theory against real life. We fill this gap by conducting exploratory research in Sustainable Entrepreneurship, identifying the entrepreneurs motivations to start-up their unique venture, challenges faced throughout the venture development process and their impact within their defined market. It is evident throughout the five case studies all our entrepreneurs have encountered some sort of antecedent exposure to an environmental concern; leading to our belief that prior exposure to a sustainability related market failure has resulted in these entrepreneurs to pursue their business initiative. Leading from this analysis, it is evident Sustainable Entrepreneurs are highly motivated to solve environmental and/ or social related problems (sustainability-related market failures). Customer perceptions and unawareness for alternative sustainable products remain a considerable challenge. It is proposed that patents, cooperating with educational institutions, establishment of an international network and organisational culture, are all important practices that assist in the business development.