ESR may refer to:
Technology:
- Electro-slag remelting, an alloy remelting and refining process
- Electronic Staff Record, a human resources and payroll system of the UK National Health Service
- Emergency Sun Reacquisition, an attitude control mode of the Solar and Heliospheric Observatory (SOHO)
- Equivalent series resistance, the resistive parts of the impedance of certain electrical components
- ESR Technology, a UK company
- Emergency speed restriction or slow zone on British railways
- Extended Support Release, a line of Firefox developed separately, in order to maintain security.
Science:
- EISCAT Svalbard Radar
- Electron spin resonance or electron paramagnetic resonance, a technique used in chemical spectroscopy to identify unpaired electrons and free radicals
- Environmental stress cracking, a cause of unexpected brittle failure of thermoplastic polymers
- Erythrocyte sedimentation rate, the rate at which red blood cells sediment in a period of 1 hour; a medical test for inflammation
- Estrogen receptor
- European Society of Radiology
Business:
- Environmental and Social Responsibility
Other:
- Experiment In Self-Reliance, a homelessness organization in Winston-Salem, NC
- East Somerset Railway, a heritage railway in the United Kingdom
- Institute of Environmental Science and Research, a New Zealand scientific institute
- Earlham School of Religion at Earlham College in Richmond, Indiana, United States
- Eric S. Raymond, an open source software advocate
- E.S.R., Inc.
- ESR, the IATA code for the Ricardo García Posada Airport