In this study, we test the hypothesis that code-switching leads to phonological convergence by examining voice onset time (VOT) realization in the spontaneous code-switched speech of New Mexican Spanish-English bilinguals. We find that average VOT duration values in New Mexican Spanish fall within the range typical of non-contact varieties of the language, while New Mexican English displays VOT values in the low range of typical non-contact English. When we examine the VOT values of Spanish- and English-language words at varying degrees of proximity to code-switch points, we find a similar asymmetry. In Spanish, no effect of recent code-switching is evident. In English, conversely, close proximity to code-switch points results in a significant reduction in VOT values, i.e. in the direction of Spanish. We argue that while the data studied here do not directly demonstrate a causal connection between code-switching and long-term phonological convergence, they would not be inconsistent with such a view. We discuss a number of possible causes for the observed asymmetry between Spanish and English.