This article reports on an experiment comparing the effects of three discrete types of deviance from native language (L1) phonetics and phonology on verbal short-term memory performance. A nonword repetition task was used to measure the recall of four stimulus types: (a) high-probability L1-sounding nonwords, (b) low-probability L1-sounding nonwords, (c) nonwords containing illegal L1 phoneme sequences, and (d) nonwords containing non-L1 sound segments. Special response assessment criteria were used in order to control for potential production effects such as an accent. Results reveal a major detrimental effect caused by the presence of unfamiliar sound segments in the input. The decrement produced by phonological deviances was only significant in the case of long (six-syllable) stimuli. A model of LTM-STM interaction is proposed in which the supporting effect of phonetic knowledge is restricted to perceptual analysis and the role of phonological/phonotactic knowledge is confined to reconstructive processes.