•
Macedonian Scientific Institute, an institution in Sofia, Bulgaria •
Marketing Science Institute, a nonprofit learning institution in Cambridge, Massachusetts, US •
Media Sport Investment, the international fund of investors that ran Sport Club Corinthians Paulista •
Millennium Science Initiative, an international program bringing technology to developing nations •
Ministry of Science and Innovation (New Zealand) •
Minority-serving institution, in US higher education •
MSI Reproductive Choices, an international non-governmental organisation providing contraception and safe abortion services, with a global HQ in London, UK •
Museum of Science and Industry (Chicago), US •
Science and Industry Museum, in Manchester, England •
University of Minnesota Supercomputing Institute •
Italian Social Movement (
Movimento Sociale Italiano), a defunct post-fascist party
Companies •
Micro-Star International, a Taiwanese information technology company •
Midwest Scientific Instruments, a defunct American computer company •
Morgan Stanley (Broker ID), an American financial services company •
Motorola Solutions (NYSE: MSI), an American data communications and telecommunications equipment provider •
Movie Star (company) (AMEX: MSI), an American clothing manufacturer ==Science and technology==