The use of volunteers by natural resource managers has become quite widely accepted, but the development of programs where tourists volunteer and make a financial contribution is less widespread. This article focuses on one type of volunteer vacation or conservation holiday, where participants pay to work as volunteers helping conduct environmental field research. It is a developing area that increasingly is being recognised by potential travellers as a holiday choice. Importantly participatory environmental research trips also provide scientists with an alternative means of funding research and another vehicle through which to achieve goals. These types of programmes allow tourism to actively support conservation and sound ideal, but there are also significant constraints and issues. Varying partnerships and operating structures impact on the resulting benefits and costs for all stakeholders. This article defines and examines the global development of the Participatory Environmental Research Tourism (PERT) sub-sector. By exploring the existing activities within the sub-sector it is hoped to highlight operating characteristics, current logistical constraints and stimulate further research.