MSS may refer to:
Places
- Manassas (Amtrak station) (station code), Virginia, US
- Massena International Airport (IATA code), New York, US
- Moses Gate railway station (National Rail station code), England
Organizations
Education
- Monkton Combe School, near Bath, UK (for Monkton Senior School)
- Montserrat Secondary School, Salem, Montserrat (British Overseas Territory)
- Midland Secondary School, Ontario, Canada
- Marymount Secondary School, Hong Kong, China
- Marsiling Secondary School, Singapore
- Master of Strategic Studies, awarded by military colleges such as Marine Corps University
Other organizations
- Ministry for State Security (disambiguation), multiple organizations
- Merseyside Skeptics Society, UK, for scientific scepticism
- The Mother's Service Society, a social science research institute in Pondicherry, India
- Manufacturers Standardization Society, an organization in the Valve and Fittings Industry
Science and technology
Computing
- Managed security service, in outsourced networks
- Mass Storage System, the IBM 3850
- Maximum segment size, a TCP header parameter in computer networking
- Microsoft Search Server
- Miles Sound System, a sound software development kit for video games
Other science and technology
- Marshall–Smith syndrome, characterized by unusual accelerated skeletal maturation
- Microsatellite stability, in genetics
- Multispectral Scanner, on Landsat satellites
- Mobile Servicing System, a robotic system on board the International Space Station
- Mobile switching centre server, in mobile telephony
- Mobile-satellite service, in telecommunications
- Monosulfide Solid Solution, a phase of paragenesis
Other uses
- Modern Shetlandic Scots, a name for Shetland dialect used by some linguists
- Modular Sleep System, a US forces sleeping bag
- MSS or Mss., an abbreviation for manuscripts (handwritten documents)