Time‐resolved electron‐beam diagnostics have been developed for use with free‐electron lasers (FELs) and associated electron sources, based on the techniques of secondary electron emission and optical transition radiation (OTR). The 32‐channel OTR detector forms part of a high‐resolution (0.18%) electron spectrometer with a time resolution of 50 ns. Variable‐magnification optics allow the spectrometer to view single‐macropulse spectra with widths in the range of 0.2%–7%; wider spectra are taken with several momentum settings. Design criteria for the spectrometer are presented, and experience of operating with the diagnostics over a range of FEL physics experiments is summarized. The spectrometer is used, in conjunction with optical diagnostics, in studies at FELIX of efficiency enhancement, pulse chirping, and stepped‐undulator operation. ©1996 American Institute of Physics.