American Jewish Service

Offers Volunteer Summer, a service-learning program for Jewish high school seniors and adults (16-24) that includes community volunteer projects in the developing world.

Catholic Network of Volunteer Service

A non-profit membership organization of 200 domestic and international volunteer and lay mission programs.

A non-profit international volunteer organization that operates programs in Brazil, China, Costa Rica, Ghana, Guatemala, India, Peru, Russia, Tanzania, and Thailand.  Volunteers work side-by-side with local people on community-driven projects that foster cultural understanding.

EarthWatch

An international non-profit organization that brings science to life for people concerned about the Earth's future.

Global Volunteers 

A non-governmental organization that has special consultative status with the United Nations, represents local leaders in an international arena, and engages short-term volunteers in local development efforts.

How to Live Your Dream of Volunteering Overseas

This website, based on the book by Joseph Collins, Zahara Heckscher, and Stefano DeZerega, has a section devoted to resources for overseas volunteers.

Idealist.org 

This organization offers Action Without Borders, a program that connects people, organizations and resources to find practical solutions to social and environmental problems.

Institute for Global Education and Service-Learning

A non-profit training organization that creates service-learning programs and initiates activity-based education in collaboration with schools and organizations around the world.

International Partnership for Service-Learning

A non-profit educational organization incorporated which serves students and organizations around the world by fostering programs that link volunteer service to academic study and the community.

International Volunteer Programs Association 

An alliance of non-profit, non-governmental organizations which are based in the Americas and involved in international volunteer and internship exchanges. 

JDC Jewish Service Corps 

Corps members serve for one year as a volunteer in overseas Jewish communities, organizing Jewish educational, cultural, social and religious programs with the goal of promoting Jewish identity and helping the community become more self-sufficient.

Peace Corps  

This federal government agency trains volunteers to serve in 139 host countries working on issues ranging from AIDS education to information technology and environmental preservation. 

United Planet 

This cultural exchange organization supports members and volunteers in over 150 countries who foster global understanding and friendship, support communities in need, and promote social & economic prosperity.

Volunteers for Peace International Work Camps  

This organization provides programs where people from diverse backgrounds can work together to help overcome the need, violence and environmental decay facing the planet. 

WorldTeach 

WorldTeach volunteers usually teach English, though placements have also expanded into other fields such as information and communication technology and environmental education.