- Alceon - Human Health & Ecological Risk Assessment Services - Offers services in environmental science and engineering, including health and ecological risk assessment, toxic substances, litigation support, and expert testimony
- Capaccio Environmental Engineering, Inc. - Environmental engineering and consulting to industry for air pollution control, water/wastewater treatment, hazardous waste management, and pollution prevention.
- Cochrane associates, Inc. - environmental engineering, web site consulting, environmental software
- Environmental Sampling & Testing, Ltd. - Environmental Sampling & Testing, Ltd. provides a wide range of environmental services and consulting throughout the New England States.
- Karl Eklund, Ph.D., L.S.P. - Hazardous Waste Site Cleanup and other environmental consulting
- Tellus Institute - A non-profit research and consulting organization that works on resource management and environmental issues.
- Tighe and Bond - Environmental engineering specializing in water and wastewater projects.