Two experiments examined the generalizability of the effects of word length and phonological similarity with visual and auditory presentation in immediate verbal serial ordered recall. In Experiment 1, data were collected from 251 adult volunteers drawn from a broad cross-section of the normal population. Word length and phonological similarity in both presentation modes significantly influenced the group means. However, 43% of the subjects failed to show at least one of the effects, and the likelihood that effects appeared was highly correlated with verbal memory span. In Experiment 2, 40 subjects of the original sample were retested, 20 of whom had failed to show one or more effects in Experiment 1. Whether or not an effect had appeared for individual subjects on the first test session was a poor predictor of whether the effect would appear on retest. Finally,an analysis of subject reports demonstrated that the patterns of experimental data could be accounted for in part by the strategies that subjects reported using, and the effect of strategy was independent of the effect of span. The implications of these findings for theories of verbal short-term memory are discussed.Current views as to the characteristics of verbal shortterm memory owe much to the discovery and exploration of the effects on immediate serial ordered recall of word length and phonological similarity. The word-length effect refers to the tendency for normal adult subjects to have more difficulty in immediate serial ordered recall of a sequence oflong words (e.g., university, aluminium, hippopotamus, refrigerator) than in that of a sequence of short words (e.g., scroll, switch, zinc, maths). The phonological similarity effect arises from the relative difficulty in serial ordered recall of phonologically similar items (e.g., man, mad, map, mat) compared with recall ofa sequence of items that are phonologically distinct (e.g., day, boy, sup,few). Word-length and phonological similarity effects appear whether the subjects read or listen to the word sequence for recall.These are robust effects that have been replicated widely with a range of materials using groups of normal subjects (e.g., Baddeley, Thomson, & Buchanan, 1975; Caplan, Ro-Part ofthe work on which this paper is based was supported by a travel grant given to the first author from the Trustees of the journal Brain. We are grateful to Alan Baddeley for very helpful discussions on this topic, and to Marc Marschark for useful discussions on the incidence of head injury in the college population. We are also grateful to Nelson Cowan