Previous work on frequency has in the main focused on paradigmatic aspects such as irregularity and allomorphy. This study, in contrast, addresses the syntagmatic dimension and in particular examines the effect of token frequency on serial order. A simple prediction follows from the psycholinguistic observation that frequency facilitates the retrieval of linguistic units: frequent units should precede infrequent ones rather than vice versa in the linear representation of speech. This prediction is tested on a total of fourteen phenomena from various languages and found to receive wide support in the domain of word order. However, it exerts only a sporadic influence on morpheme order and apparently no influence on phoneme order. Frequency is argued to be a cost-free, explanatory and pervasive, albeit a relatively weak factor. It is most likely to manifest itself in areas where alternative ordering options are available which are also semantically similar. Frequency may accompany linguistic change through its various stages.