Significance The circadian clock controls daily rhythms in genes involved in a wide range of biological processes, including signal transduction, cell division, metabolism, and behavior. The primary focus on understanding clock control of gene expression has been at the level of transcription. However, in many systems, there are examples of proteins that accumulate rhythmically from transcripts that are constitutively expressed. These data suggested that the clock regulates translation, but the underlying mechanisms were largely unknown. We show that the clock in Neurospora crassa controls the activity of translation elongation factor-2 (eEF-2) and that regulation of translation elongation leads to rhythmic translation in vitro and in vivo. These studies uncover a mechanism for controlling rhythmic protein accumulation.