Costello Insurance Agency Inc.
- A.I.M. Mutual Insurance Companies
- Acadia
- AIG
- American European
- American Modern Insurance Group
- AmeriTrust
- AmTrust
- Arbella Insurance Group
- Berkshire Hathaway GUARD
- Bunker Hill Insurance
- Chubb
- CNA
- Concord Group Insurance
- Coverys
- FirstComp
- Foremost
- GNY
- Great American
- Hanover
- Harleysville
- Hartford
- Heritage
- Homeowners Choice
- Hospitality Ins.
- Liberty Mutual
- MAPFRE
- MAPFRE
- MEMIC
- Merchants Insurance Group
- MiddleOak
- Narragansett Bay
- Nationwide
- NGM/Main St. America
- OneBeacon
- People's Trust
- Philadelphia
- Pilgrim
- Plymouth Rock Assurance
- Preferred Mutual
- QBE
- Quaker Special Risk
- Quincy Mutual Group
- RPS
- Ryan Turner Specialty
- Safeco
- Safety Ins.
- State Auto
- Travelers
- TypTap
- Union Mut.
- Universal NA
- Universal Property
- Utica First
- Utica National Insurance Group
- William J. Costello, Pres.