Langan Engineering, Environmental, Surveying, Landscape Architecture and Geology D.P.C.
Langan Engineering and Environmental Services, LLC 
Langan MA, Inc.
Langan CA, Inc.
Langan International, LLC 
Langan International UK, Ltd.
Langan Panama LLC
Langan Panama, S. DE R.L.
Langan CT, Inc.
Langan MI, Inc.
Langan NC, Inc.