A Thomson scattering diagnostic capable of achieving one‐discharge, high‐resolution spectra through use of a microchannel plate image intensifier coupled to an optical multichannel analyzer has been implemented on a theta‐pinch device. The improved resolution permits measurements of local average electron velocities and current densities. First‐order relativistic corrections and anomalous velocity‐space fluctuations are directly observable. The enhanced fluctuations are attributed to electrons interacting with unstable waves.