The zoological sector has a responsibility to reduce its environmental impacts and extend its positive contribution to society, in accordance with its commitment to sustainable development. This paper focuses on how zoos and aquariums (‘zoos’) can improve their sustainability performance using a Triple Bottom Line (TBL) framework. This framework helps to identify and shape how the ecological integrity and social contributions of zoos can be upheld and enhanced alongside economic commitments. Only when these three elements are in balance will a more sustainable outcome be achieved. This paper describes zoo-based functions that fit within the TBL framework to suggest how zoos may best improve their sustainability performance. The paper includes results from a 2007 survey conducted by the author involving 52 British & Irish Association of Zoos & Aquariums member zoos.