For specific information about adopting in Guatemala:

U.S. Department of State
http://travel.state.gov/adoption_guatemala.html

The Joint Council on International Children's Services
http://www.jcics.org/guatemala.html

For general information about international adoption:

U.S. Department of State
http://travel.state.gov/adopt.html

The Joint Council on International Children's Services
http://www.jcics.org

The Hague Conference on Private International Law
http://www.hcch.net/e/index.html

For general information about adoption:

National Adoption Information Clearinghouse
http://www.calib.com/naic

Center for Adoption Support and Education
http://www.adoptionsupport.org

The Adoption Guide
http://www.theadoptionguide.com

National Adoption Center
http://www.adoptnet.org

North American Council on Adoptable Children
http://www.nacac.org

For information on children's issues:

The Children's Bureau - U.S. Department of Health and Human Services
http://www.acf.dhhs.gov/programs/cb

Child Welfare League of America
http://www.cwla.org