- Singing River Hospital
- Sino Television, Inc.
- Sioux Center Health Avera
- Sioux City Fire Rescue
- Sioux County Courthouse
- Sioux Empire United Way, Inc.
- Siouxland Community Health Center
- Sirsi
- Sister Cities International
- Sisters of Charity Hospital
- Sisters of Charity Hospital, St. Joseph Campus
- Sisters of Providence Health Systems- Mercy Medical Center
- Sisters of the Catholic Apostolate Pallottines)
- Sisters, Servants of the IHM
- Sistersville General Hospital
- SITE Group
- Sitescape
- SIU Medicine Springfield Residency Program
- Skagit County
- Skanska USA Building Inc.
- Skidmore Owings and Merrill LLP
- Skiff Medical Center
- Skokie Hospital
- Sky Insurance
- Sky Ridge Medical Center
- Skyline Exhibits-The Holt Group Inc.
- Skywest Airlines
- Slakey Bros.
- Sleep Inn
- Sleep Inn Jackson
- Sleep Inn, Florence
- SLEH-THI
- Slidell Memorial Hospital
- Slimfast Nutritional Foods
- Slosman Corp.
- Slovenian Savings and Loan Assoc., Franklin-Conemaugh
- SMACTIP
- Small Business School
- Small Market Meetings, Pioneer Publishing, Inc.
- Smart Brief
- SMART Caregiver Corporation
- Smart Kids Software
- SME Steel
- Smith Anderson Law Firm
- Smith Appraisals
- Smith Food and Drug
- Smith International Inc.
- Smith Street Church
- Smith Travel Research
- SmithBucklin