The green chemistry revolution is providing an enormous number of challenges to those who practice chemistry in industry, education and research. With these challenges however, there are an equal number of opportunities to discover and apply new chemistry, to improve the economics of chemical manufacturing and to enhance the much-tarnished image of chemistry. In this article which is based on his Inaugural Lecture at the University of York in 1998, Professor Clark reviews some of the challenges, considers some of the new and successful “greener” chemistry in practice and uses two areas of chemistry to examine the scale and diversity of current problems and the exciting opportunities for innovative chemistry research and application.