Although it is generally accepted that the word length effect in short-term memory operates through output delay or interference, there is less agreement on whether it also influences performance through its impact on rehearsal. We investigated this issue by studying the effect of word length on recall and on a recognition task in which output delay was controlled. Word sequences were repeated exactly, or with one pair of words reversed. Two experiments using auditory presentation showed clear word length effects for both recall and serial recognition, although the magnitude of the effect tended to be less for recognition. A third experiment using visual presentation studied the effect of articulatory suppression during the recognition test; again we found a clear word length effect. It is concluded that the word length effect can influence retention through both rehearsal and output factors, as proposed by the phonological loop hypothesis.