Polysyllabic shortening is used to maintain stress-timed rhythm in English, but used negligibly in Spanish. It is unknown how polysyllabic shortening is influenced when individuals are exposed to one language that employs it and one that does not. We calculated polysyllabic shortening for 35 functionally monolingual English-speaking adults and 19 relatively balanced Spanish–English bilingual peers who repeated English and Spanish nonwords. Results showed that speech motor patterns learned early in life might be sufficient to block cross-linguistic transfer of polysyllabic shortening despite limited language proficiency, and bilingual speakers appear to signal membership in the majority language by increasing polysyllabic shortening.