Twenty monolingual English speakers and 40 native Spanish speakers, who were either relatively proficient or nonproficient in English, produced English /p/ at self-selected normal and fast speaking rates. The native English (NE) subjects showed much the same rate effect on voice onset time (VOT) seen in earlier studies. Native Spanish (NS) subjects who were relatively proficient in pronouncing English used fewer short-lag stops and showed an English-like rate effect on VOT. NS subjects who were relatively nonproficient in English, on the other hand, used more short-lag stops and did not show a significant speaking rate effect on VOT, although they did demonstrate speaking rate effects on vowel duration and phrase duration. Among the NS subjects were 21 whose VOT values closely matched those of the NE subjects at both speaking rates, and who showed a rate effect similar to that found for the NE subjects. Their ability to modify VOT across speaking rates suggested that these NS subjects may have established a phonetic category for English /p/. © 1995 S. Karger AG, Basel.