Below are some institutions and organizations working on ecology and sustainable-development projects.

Earthwatch Institute (tel. 800/776-0188; www.earthwatch.org) organizes volunteers to go on research trips to help scientists collect data and conduct field experiments in a number of scientific fields. Expeditions to Ecuador range from studies of cloud-forest birds to aiding efforts to eliminate the exotic species that threaten the ecological equilibrium of the Galápagos Islands. Fees for food and lodging average around $2,500 (£1,667) for a 2-week expedition, excluding airfare.

Ecuador Volunteer (tel. 02/2557-749; www.ecuadorvolunteer.org), a Quito-based organization that connects volunteers with nonprofit organizations, usually has positions available at local environmental organizations.

Global Volunteers (tel. 800/487-1074 in the U.S.; www.globalvolunteers.org) is a U.S.-based organization that offers a unique opportunity to travelers who've always wanted a Peace Corps-like experience but can't make a 2-year commitment. For 2 to 3 weeks, you can join one of its working vacations in Ecuador. A certain set of skills, such as engineering or agricultural knowledge, is helpful but by no means necessary. Each trip is undertaken at a particular community's request, to complete a specific project. However, be warned: These "volunteer" experiences do not come cheap. You must pay for your transportation as well as a hefty program fee, around $2,495 (£1,663) for a 2-week program.

Habitat for Humanity International (tel. 229/924-6935, ext. 7530 in the U.S.; www.habitat.org) has chapters in Ecuador and sometimes runs organized Global Village programs here.

The Idealist (www.idealist.org), a Web portal of volunteer and employment opportunities with nonprofit organizations around the world, often lists more than a dozen environmental volunteer positions in Ecuador.

Jatun Sacha (tel. 02/2432-240; www.jatunsacha.org) is an Ecuadorean environmental foundation that manages private biological reserves in various parts of the country and works with local communities to involve them in conservation. They accept a steady flow of volunteers who help with field research, teach English, and perform other tasks for fees that are a fraction of what big U.S. volunteer programs charge.

Maquipucuna (tel. 706/542-2923 in the U.S.; www.maqui.org) is a private biological reserve and ecotourism lodge in the northern Pacific lowlands that is administered by the University of Georgia. They accept volunteers to help with conservation and research projects; volunteers pay $450 (£300) per month for food and lodging. The reserve protects an important expanse of the endangered Chocó rainforest.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.