Field effect may refer to: relative influence of electricity to the substrate within a given field.

• Field effect (chemistry), an effect that a pole (either an unipole or dipole) has on a remote reaction centre (reaction rates, equilibrium). This effect operates through space not through bonds which distinguishes it from the inductive effect.
• Field effect (semiconductor), the physical mechanism modulating the conductivity of a semiconductor using an applied voltage difference.
• Field effect also known as field cancerization, a field of molecular and cellular changes in normal appearing tissue, which predispose to the development of cancer.
• Wien effect, in electrolytes, an increase in ionic mobility or conductivity of electrolytes at very high gradient of electrical potential.