There is a need for new, biologically-based crop protection products to serve as alternatives to or to complement synthetic chemical pesticides. An interdisciplinary research team from the natural and social sciences considered whether regulatory barriers were preventing more biopesticides reaching the market. The research coincided with a realisation by policy makers that more needed to be done to facilitate biopesticide registration, exemplified by the UK's Biopesticides Scheme. However, important differences remain between the UK and other countries such as the USA. Changes in regulatory arrangements need careful handling. The scientific work undertaken in the project provided a better understanding of the population biology of microbial control agents. Interdisciplinary work permitted a contribution to the policy debate.