HereZeffprofiles have been obtained across the entire minor radius of the DIII‐D [Fusion Technol.8, 441 (1985);PlasmaPhysicsandControlledNuclearFusionResearch,1986(IAEA, Vienna, 1987), Vol. 1, p. 159] tokamak from measurements of visible bremsstrahlung continuum radiation. TheZeffprofiles are presented for Ohmic divertor and limiter plasmas as well as for neutral beam heated H‐mode and L‐mode plasmas. The measuredZeffprofiles are found to have small gradients over the entire plasma cross section. This implies that resistivity gradient driven electrostatic modes are unlikely to influence the confinement properties in the edge region of these discharges. The H‐mode plasma has a centrally peakedZeffprofile and a relatively flat electron density profile that suggests the existence of a negative value for the parameter &eegr;i.