Direct measurements using a picosecond streak camera have shown that transform‐limited pulses having durations ∼5 psec are produced throughout the pulse train of a mode‐locked neodymium‐phosphate glass laser operating in the TEM00mode. Under the conditions of higher‐power multimode operation, bandwidth‐limited pulses are generated in the initial part of the train only. Spectral and temporal broadening due to intensity‐dependent nonlinear effects are observed as the higher‐power mode‐locked trains evolve.