- Anthony, Earle C8
- Antonelli, Paola1
- Antoni Tadross & Co.1
- Antozone Chemical Co.1
- Antry Realty Corp.1
- Appel, Henry J.2
- Arbeit, Arnold A.10
- Arbuckle Bros.4
- Arbuckle-Ryan Co.2
- Arbuckles & Co.1
- Arbuthnot, Stephenson & Co.1
- Arcadia Realty Corp.1
- Architects Collaborative1
- Architects Design Group8
- Architects and Engineers Affiliates1
- Architectural Iron Works (Firm)1
- Architectural League of New York3
- Ardale Building Corp.1
- Ardlan Construction Co., Inc.1
- Arende Building Corp.1
- Argent Construction Corp.1
- Argot Construction Corp.1
- Argus Company1
- Arista Realty Corp.1
- Arizona State University2
- Arkell Weekly Co.1
- Arlen, Samuel S.1
- Arlington Terrace, Inc.3
- Armory Estates, Ltd.5
- Armour, M. Cochrane1
- Armstrong, Andrew, 1910-198317
- Armstrong, Florence, 1910-200417
- Armstrong, Lorenzo D.1
- Arner, Douglas G., 1926-20061
- Arnley Construction Co., Inc.1
- Arno Realty Corp.1
- Arnold M. Goldman Co.1
- Arnold M. Goldman and Co., Inc.23
- Arnold, C. D. (Charles Dudley), 1844-192764
- Aronin, Jeffrey Ellis, 1927-2
- Aronowitz, Stanley3
- Arrowbrook Garden Corp.3
- Arsmith Realty Co., Inc.1
- Art Institute of Chicago1
- Art Stove Company1
- Artcourt Realty Co.1
- Arthold Realty Co.1
- Arthur & Bonnell1
- Arthur Eckstein, Inc.1
- Arthur Hardgrove Co.15
- Artpaul Realty Co., Ltd.10
- Arts Council of Great Britain3
- Arts Park9
- Arts and Entertainment Network1
- Artsis, Jerome M.3
- Arwin Construction Corp.1
- Asch, Stephen1
- Ascot Estates, Inc.1
- Ashepoo Phosphate Co.1
- Asher Dann and Sons5