| DUNBAR & SONS CO., INC.Harwinton, CT · Dissolved | Harwinton, CT | Corporation | Mar 29, 1954 | Dissolved |
| LEONARDI BUILDING COMPANY, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Jan 4, 1966 | Active |
| LUCAS PAVING COMPANY, INC.Harwinton, CT · Dissolved | Harwinton, CT | Corporation | Feb 5, 1973 | Dissolved |
| LEONARDI ENTERPRISES, INC.Harwinton, CT · Forfeited | Harwinton, CT | Corporation | Jan 8, 1965 | Forfeited |
| MAIN STREET BRISTOL HOLDINGS, INC.Harwinton, CT · Dissolved | Harwinton, CT | Corporation | Sep 26, 1958 | Dissolved |
| HARWINTON DRILLING & ENGINEERING COMPANY, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Aug 18, 1969 | Active |
| COVENTRY LANE HOMEOWNERS, ASSOCIATION, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Jun 16, 1976 | Active |
| E. F. "SAM" GRENUCK MEMORIAL SCHOLARSHIP FUND, INC.Harwinton, CT · Dissolved | Harwinton, CT | Corporation | Dec 13, 1971 | Dissolved |
| HARWINTON AMBULANCE ASSOCIATION, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | May 14, 1963 | Active |
| HARWINTON HISTORICAL SOCIETY INCORPORATEDHarwinton, CT · Active | Harwinton, CT | Corporation | Dec 17, 1970 | Active |
| HARWINTON LAND CONSERVATION TRUST, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Jan 2, 1973 | Active |
| HARWINTON ROD & GUN CLUB, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Dec 19, 1969 | Active |
| HARWINTON TENNIS CLUB, INCORPORATED, THEHarwinton, CT · Active | Harwinton, CT | Corporation | Nov 5, 1953 | Active |
| THEODORE A. HUNGERFORD MEMORIAL MUSEUM ASSOCIATION, INCORPORATEDHarwinton, CT · Active | Harwinton, CT | Corporation | Dec 15, 1927 | Active |
| HARWINTON VOLUNTEER FIRE DEPARTMENT, INCORPORATED THEHarwinton, CT · Active | Harwinton, CT | Corporation | May 26, 1944 | Active |
| HARWINTON WEST SIDE VOLUNTEER FIRE COMPANY, INCORPORATED, THEHarwinton, CT · Active | Harwinton, CT | Corporation | Oct 17, 1955 | Active |
| HIGH RIDERS SNOWMOBILE CLUB, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Mar 3, 1969 | Active |
| IVES-CLEVELAND AMERICAN LEGION POST NO. 137 "INC."Harwinton, CT · Active | Harwinton, CT | Corporation | Feb 11, 1964 | Active |
| KINGDOM GAME CLUB,INCORPORATED,THEHarwinton, CT · Active | Harwinton, CT | Corporation | Sep 15, 1955 | Active |
| LA LECHE LEAGUE OF CONNECTICUT, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Oct 9, 1975 | Active |
| LITCHFIELD COUNTY ANTIQUE FIRE COMPANY INC.Harwington, CT · Forfeited | Harwington, CT | Corporation | Mar 11, 1971 | Forfeited |
| FRANK RONDANO INCORPORATEDHarwinton, CT · Active | Harwinton, CT | Corporation | Nov 21, 1949 | Active |
| ENERGY RESEARCH GROUP, INC.Harwinton, CT · Forfeited | Harwinton, CT | Corporation | Dec 21, 1979 | Forfeited |
| P.M.S. ENTERPRISES, INC.Harwinton, CT · Dissolved | Harwinton, CT | Corporation | Apr 21, 1981 | Dissolved |
| HARWINTON LIBRARY FRIENDS, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Jan 25, 1982 | Active |
| STAN POLLOCK BUILDING & REMODELING, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Jul 1, 1982 | Active |
| NORTHWEST COMMUNICATIONS, INC.Harwinton, CT · Dissolved | Harwinton, CT | Corporation | Jul 8, 1982 | Dissolved |
| CAL BUSINESS SOLUTIONS INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Aug 17, 1982 | Active |
| Duksa USA Ltd.Harwinton, CT · Active | Harwinton, CT | Corporation | Sep 21, 1982 | Active |
| M.R. BART CONSTRUCTION, CORP.Harwinton, CT · Active | Harwinton, CT | Corporation | Jan 10, 1983 | Active |
| BROOKFIELDS PROPERTY OWNERS ASSOCIATION, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | May 23, 1983 | Active |
| DURSTIN MACHINE & MANUFACTURING, INC.Harwinton, CT · Forfeited | Harwinton, CT | Corporation | Feb 14, 1984 | Forfeited |
| PATELLA'S, INC.Harwinton, CT · Forfeited | Harwinton, CT | Corporation | Jul 29, 1985 | Forfeited |
| PERSONALIZED TRAVEL, INC.Harwinton, CT · Dissolved | Harwinton, CT | Corporation | Jan 2, 1986 | Dissolved |
| THE SUPREME GROUP, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Apr 22, 1986 | Active |
| BERKSHIRE SUPPLY, INC.Harwinton, CT · Forfeited | Harwinton, CT | Corporation | Jul 9, 1986 | Forfeited |
| LAFFERTY ENTERPRISES, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Sep 10, 1987 | Active |
| EASTSIDE ELECTRIC, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Sep 22, 1987 | Active |
| B & R CORPORATIONHarwinton, CT · Active | Harwinton, CT | Corporation | Oct 19, 1987 | Active |
| LETOURNEAU BUILDING CORPORATIONHarwinton, CT · Dissolved | Harwinton, CT | Corporation | Jan 11, 1988 | Dissolved |
| HYDRAULIC ENGINEERING CORPORATIONHarwinton, CT · Dissolved | Harwinton, CT | Corporation | Mar 16, 1988 | Dissolved |
| NORTHWEST ELECTRICAL CONSTRUCTION CORPORATIONHarwinton, CT · Active | Harwinton, CT | Corporation | Jun 1, 1988 | Active |
| FABCON, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Jul 1, 1988 | Active |
| H Y S A, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Dec 29, 1988 | Active |
| BROOKFIELD CONSTRUCTION COMPANY, INC.Harwinton, CT · Dissolved | Harwinton, CT | Corporation | Mar 16, 1989 | Dissolved |
| LETOURNEAU REALTY ASSOCIATES, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Jan 22, 1990 | Active |
| LETOURNEAU BROTHERS BUILDING CORPORATIONHarwinton, CT · Dissolved | Harwinton, CT | Corporation | Jan 22, 1990 | Dissolved |
| QUALITY LAWN, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Jan 25, 1990 | Active |
| HARWINTON POST NO. 7008 VETERANS OF FOREIGN WARS OF THE UNITED STATES, INC.Harwinton, CT · Dissolved | Harwinton, CT | Corporation | Feb 8, 1990 | Dissolved |
| 103 BANK STREET CONDOMINIUM ASSOCIATION, INC.Harwinton, CT · Active | Harwinton, CT | Corporation | Apr 9, 1990 | Active |