| Name | Phone | Category |
| A B C Sign Corporation | (203) 335-3403 | Retail |
| A. J. Gambardella Associates LLC | (203) 377-8455 | Insurance Services |
| AMC Environmental, LLC | (203) 378-5020 | Environmental Testing & Consulting |
| A. P. Construction Company | (203) 388-1136 | Contractors - General |
| A Place For Mom | (866) 355-6988 | Social Service Organizations |
| A & S Pharmaceutical Corp | (203) 368-2538 | Pharmacy & Pharmaceutical |
| A. DiCesare Associates, PC | (203) 696-0444 | Engineering |
| AAA Nursing Care, LLC | (203) 377-2220 | Home Health Care |
| Abbey Tent & Party Rentals | (203) 368-6111 | Rentals-Tent, Party etc. |
| Action For Bridgeport Community Development, Inc. | (203) 366-8241 | Non-Profit Organizations |
| ADECCO Employment Services | (203) 386-0127 | Employment Agency/Recruitment/Staffing |
| Adkins Design | (203) 880-9517 | Advertising - Promotions |
| AD-MERICA Corporation | (203) 929-4708 | Advertising - Promotions |
| ADP Automatic Data Processing | (203) 882-7590 | Human Resource Services |
| Advanced Back & Neck Center | (203) 333-8645 | Physical Therapy |
| Advanced Radiology Consultants | (203) 696-6125 | Hospitals |
| Adzima Funeral Home, Inc. | (203) 375-2200 | Funeral Services & Supplies |
| AETNA | (860) 273-1775 | Insurance Services |
| AFB Management | (203) 275-8370 | Construction Management |
| AFLAC | (203) 650-1879 | Insurance Services |
| Ahlbin Centers for Rehabilitation Medicine | (203) 336-7301 | Non-Profit Organizations |
| Akdo Intertrade Incorporated | (203) 336-5199 | Export & Import Service |
| AKF Marketing | (203) 540-7740 | Marketing Services |
| Akoya Asian Cuisine | (203) 381-9366 | Restaurants |
| Carl J. Alber CPA | (203) 377-9797 | Certified Public Accountants |
| Albertus Magnus College New Dimensions Program | (800) 394-9982 | Schools/Colleges/Educators |
| Alinabal Inc. | (203) 877-3241 | Manufacturers |
| All American Appliance | (203) 261-3210 | Appliance Sales & Service |
| All Around Contracting Corp | (203) 908-3365 | Contractors - General |
| All League Embroidery | (203) 377-7215 | Advertising - Promotions |
| Alloy Engineering Company Inc. | (203) 366-5253 | Manufacturers |
| Al's Angels | | Non-Profit Organizations |
| American Heart Association | (914) 640-3266 | Non-Profit Organizations |
| American Medical Response | (203) 332-4080 | Health Care |
| American Red Cross | (877) 287-3327 | Non-Profit Organizations |
| American SIGNS & Designs | (203) 259-3300 | Signs |
| American View Productions LLC | (203) 366-5033 | Audio-Visual-Video-TV Production |
| Amerigas | (203) 330-9852 | Propane |
| Ameriprise Financial | (203) 378-0699 | Financial Services |
| AMS Real Estate, LLC | (203) 372-1200 | Real Estate |
| Amsoil | (203) 459-1508 | Synthetic Lubricants |
| Angel Commercial Real Estate | (203) 335-6600 | Real Estate Agencies |
| Anthem Blue Cross and Blue Shield | (203) 239-8757 | Insurance Services |
| Antinozzi Associates Architecture & Interior Design | (203) 377-1300 | Architects |
| Aquarion Company | (203) 336-7628 | Utility Companies |
| Ash Creek Enterprises | (203) 572-0200 | Computer Services & Equipment |
| Ash Creek Saloon | (203) 333-2733 | Caterers |
| Ashcroft Inc. | (203) 378-8281 | Manufacturers |
| Associated Appliance | (203) 445-9546 | Retail |
| Associated Builders and Contractors of CT | (203) 870-8251 | Construction Equipment, Services & Materials |
| Associated Resources Int'l LLC | (203) 380-2626 | Fulfillment - Distribution |
| AT & T Mobility | (203) 374-6658 | Telecommunication Services |
| A.T. Tavella LLC | (203) 381-9775 | Insurance Services |
| AT&T | (203) 771-4617 | Telecommunication Services |
| Atria Assisted Living | (203) 380-0006 | Assisted Living Facilities |
| Automated Building Systems, Inc. | (860) 982-2884 | Temperature Controls Contractor |
| Automated Services, LLC | (203) 877-0348 | Vending Companies |
| AV Davey Audio Visuals | (203) 372-3286 | Audio-Visual-Video-TV Production |