| 501 | Cotati Brand Eggs, Inc.Active | Corporation | Jul 2, 1990 | Active |
| 502 | De Groot Enterprises, Inc.Active | Corporation | Jun 18, 1990 | Active |
| 503 | Mcphail Fuel Co., Inc.Active | Corporation | Jun 1, 1989 | Active |
| 504 | Biotherm Hydronic, Inc.Active | Corporation | Feb 10, 1989 | Active |
| 505 | Trimyc Mechanical, Inc.Active | Corporation | Oct 17, 1988 | Active |
| 506 | Striping GraphicsActive | Corporation | Jan 4, 1988 | Active |
| 507 | Korean Baptist Church Of Sonoma CountyActive | Nonprofit | Aug 26, 1987 | Active |
| 508 | Nayda Of San Francisco I, A California Limited PartnershipActive | Partnership | Apr 17, 1987 | Active |
| 509 | Illingworth & Rodkin, Inc.Active | Corporation | Feb 26, 1987 | Active |
| 510 | Blk Properties, Inc.Active | Corporation | May 9, 1986 | Active |
| 511 | Palmer Roofing Service, Inc.Active | Corporation | Apr 10, 1986 | Active |
| 512 | Santa Rosa Hardware Company, Inc.Active | Corporation | Sep 10, 1985 | Active |
| 513 | Roy's Sewer Service, Inc.Active | Corporation | Aug 30, 1985 | Active |
| 514 | Greg Ledoux And Associates, Inc.Active | Corporation | Jun 15, 1984 | Active |
| 515 | Sonoma County Synagogue CenterActive | Nonprofit | Jul 1, 1982 | Active |
| 516 | Shelby Jay Bridges Enterprises, Inc.Active | Corporation | Sep 22, 1981 | Active |
| 517 | Fern Village Homeowners' AssociationActive | Nonprofit | Feb 22, 1980 | Active |
| 518 | S.r. Allied Builders, Inc.Active | Corporation | Jan 2, 1979 | Active |
| 519 | Military Officers Association Of America, Redwood Empire ChapterActive | Nonprofit | Jul 6, 1977 | Active |
| 520 | Kryolan CorporationActive | Corporation | Mar 10, 1977 | Active |
| 521 | Huffaker Engineering, Inc.Active | Corporation | Mar 18, 1976 | Active |
| 522 | Sonoma County AllianceActive | Nonprofit | Jun 11, 1975 | Active |
| 523 | Wolfard Glassblowing Co.Active | Corporation | Jun 2, 1975 | Active |
| 524 | Mahoney Contracting, Inc.Active | Corporation | Aug 30, 1974 | Active |
| 525 | Soiland Co., Inc.Active | Corporation | Mar 21, 1973 | Active |
| 526 | Monterey Import CompanyActive | Corporation | May 9, 1972 | Active |
| 527 | Sonoma County Genealogical Society, Inc.Active | Nonprofit | Dec 5, 1968 | Active |
| 528 | C & A TruckingActive | Corporation | Nov 20, 1968 | Active |
| 529 | Frontier Electric, Inc.Active | Corporation | Jan 12, 1966 | Active |
| 530 | Veterinary Associates, Inc.Active | Corporation | Nov 23, 1965 | Active |
| 531 | Venton PlasteringActive | Corporation | Apr 29, 1965 | Active |
| 532 | Cotati - Rohnert Park Nursery SchoolActive | Nonprofit | Sep 7, 1962 | Active |
| 533 | Madrone Mutual Water CompanyActive | Nonprofit | Aug 5, 1960 | Active |
| 534 | Cotati Chamber Of CommerceActive | Nonprofit | Apr 7, 1958 | Active |
| 535 | New Hope Assembly Of God Of Cotati, CaliforniaActive | Nonprofit | Feb 17, 1953 | Active |
| 536 | The Lions Club Of CotatiActive | Nonprofit | Dec 20, 1951 | Active |
| 537 | Church Of The Oaks CotatiActive | Nonprofit | Oct 18, 1907 | Active |