Name of the Subsidiary

State or Other Jurisdiction of Incorporation or Organization

Advanced GeoServices Corp.

Pennsylvania

Air, Water and Soil Laboratories, Inc.

Virginia

Analytical Environmental Services

California

Emerging Compounds Treatment Technologies, Inc.

Massachusetts

Enthalpy Analytical, LLC

Delaware

Environmental Planning Specialists, Inc.

Georgia

Envirosystems, Incorporated

New Hampshire

ES Engineering Services, LLC

Delaware

FRS Environmental Remediation, Inc

Florida

Leymaster Environmental Consulting, LLC

California

Montrose Air Quality Services, LLC

Delaware

Montrose Environmental Group AB

Sweden

Montrose Environmental Group GmbH

Germany

Montrose Environmental Group Ltd.

British Columbia

Montrose Environmental Solutions, LLC

Delaware

Montrose Foreign Holdings, Inc.

Delaware

Montrose Measurements and Analytics, LLC

Delaware

Montrose Planning & Permitting, LLC

Delaware

Montrose Services, LLC

Delaware

Montrose Waste-To-Resources, LLC

Delaware

Montrose Water and Sustainability Services, Inc.

Delaware

MSE Group, LLC

Texas

Nautilus Environmental, Inc.

California

PARS Environmental, Inc.

New Jersey

The Center for Toxicology and Environmental Health, LLC

Arkansas

CTEH Leasing, LLC

Arkansas

CTEH Properties, LLC

Arkansas

CTEH Government Services, LLC

Arkansas

CTEH IT Services, LLC

Arkansas