| SE&I | Systems Engineering and Integration 
| Others |
| SEI | Italian Entomological Socety
| Others |
| SEI | Safety Education Integrity
| Others |
| SEI | Safety Equipment Institute
| Others |
| SEI | Science and Engineering Indicators
| Others |
| SEI | Scuba Educators International
| Others |
| SEI | Seals Eastern Incorporated
| Others |
| SEI | Search Engine Inclusion
| Others |
| SEI | Search Engine Indexer
| Others |
| SEI | Search Engine Interoperability
| Others |
| SEI | Seat Ibiza
| Others |
| SEI | Secretaria Especial de Informatica
| Others |
| SEI | Security Enabling Interface
| Others |
| SEI | Security Engineers Inc
| Others |
| SEI | Security entry identifier
| Others |
| SEI | Security Equipment Inc
| Others |
| SEI | Self Enhancement Inc
| Others |
| SEI | Senhor Do Bonfim, Buenos Aires, Brazil
| Others |
| SEI | Service and Entertainment Integration
| Others |
| SEI | Service Effort and Initiative
| Others |
| SEI | Service Endpoint Interface
| Others |
| SEI | Service Express Inc
| Others |
| SEI | Servicio Extincion De Incendios
| Others |
| SEI | Set Enable Interrupts
| Others |
| SEI | Set Interrupt
| Others |
| SEI | Sew Easy Industries
| Others |
| SEI | Sewanee Environmental Institute
| Others |
| SEI | Sheltered English Immersion
| Others |
| SEI | Sheltered English Instruction
| Others |
| SEI | Simple Inference Engine
| Others |
| SEI | Sivalayam Educational Institutions
| Others |
| SEI | Smithgall Enterprises Inc
| Others |
| SEI | Social Economy Initiative
| Others |
| SEI | Socio Economic Index
| Others |
| SEI | Software Engineering Institute
| Others |
| SEI | Solar Energy International
| Others |
| SEI | Southeastern International Corporation
| Others |
| SEI | Space Exploration Initiative
| Others |
| SEI | SpaceWorks Enterprises Inc
| Others |
| SEI | Special Edition Injection
| Others |
| SEI | Special Employer Incentives
| Others |
| SEI | Special Expiration Index
| Others |
| SEI | Specific Emitter Identification
| Others |
| SEI | Specific Energy Input
| Others |
| SEI | Sports Entertainment Incorporated
| Others |
| SEI | Sportsmanship Ethics and Integrity
| Others |
| SEI | Stackpole Electronics Inc
| Others |
| SEI | Stellar Elite Intermediate
| Others |
| SEI | Stockholm Environment Institute
| Others |
| SEI | Strategic Education Inc
| Others |
| SEI | Strategic Energy Innovations
| Others |
| SEI | Strategic Equity Investments
| Others |
| SEI | Structural Engineering Institute
| Others |
| SEI | Structural Engineers Institute
| Others |
| SEI | Structured English Immersion
| Others |
| SEI | Student engagement instrument
| Others |
| SEI | Sumitomo Electric Industries
| Others |
| SEI | Summer Educational Institute
| Others |
| SEI | Superior Estimation Index
| Others |
| SEI | Supplemental Enhancement Information
| Others |
| SEI | Support Equipment Installation
| Others |
| SEI | Sustainable Electronics Initiative
| Others |
| SEI | Sustainable Endowment Institute
| Others |
| SEI | Sustainable Endowments Institute
| Others |
| SEI | Sustainable Energy Institute
| Others |
| SEI | Switch Engineering Information
| Others |
| SEI | Sykes Enterprise Incorporated
| Others |
| SEI | Syndicat des Experts Auto Independants
| Others |
| SEI | System Engineer and Integrator
| Others |
| SEI | System Engineering Instrumentation
| Others |
| SEI | Systems Engineering Integration
| Others |
| SEI | Systems Evolution Inc
| Others |
| SEI | The Seeing Eye, Inc.
| Others |