Sep or SEP may refer to:

• Sep., a common abbreviation for September
• Septentrional (borrowed from Latin meaning northern, or pertaining to the north)

• ORP Sęp (1938), a Polish Navy submarine until 1972
• ORP Sęp (2002), a Polish Navy submarine
• Splitterskyddad EnhetsPlattform, a Swedish armoured fighting vehicle

• Sep (given name)
• Hrvoje Sep (born 1986), Croatian boxer

• Secretariat of Public Education (Mexico) (Secretaría de Educación Pública)
• Specialna Enota Policije, a Slovenian National Police unit
• SEP law, Chile
• Socialist Equality Party (disambiguation), various Trotskyist political parties
• Samajik Ekta Party, Haryana, India

• Polyestriol phosphate, an estrogen medication
• Signaling End Point, in telecommunications switching
• Solar Electric Propulsion, of a spacecraft
• Solar energetic particles
• Somatosensory evoked potential, brain activity from touch
• Stanford Exploration Project, for seismic imaging of the Earth
• Standard electrode potential
• IS-1 Sęp, a 1947 Polish glider
• Somatic Experiencing Practitioner, a title used in a form of alternative psychotherapy
• sORF-encoded protein (SEP), also known as microprotein

• Stanford Encyclopedia of Philosophy
• SEP-IRA, a US pension
• Sęp, Świętokrzyskie Voivodeship, a village in Poland
• SEP Burundi (Société d'Entreposage Pétrolier au Burundi), an oil storage company
• Somebody else's problem
• Standard-essential patent, for an invention needed to meet a standard
• Syringe exchange program or needle exchange
• Summer Enrichment Program (University of Colorado), for gifted children
• Society for European Philosophy, an academic society for the study of Continental philosophy

• All pages with titles containing Sep
• Seppe (disambiguation)
• Sepp (disambiguation)
• Sept (disambiguation)
• Cep (disambiguation)