This study investigates variation in the prosodic system of Spanish in the speech of three generations of Mexican Americans living in a Mexican American-majority community in South Texas, United States, characterized by high levels of bilingualism and long-term, sustained contact between languages. Low and Grabe’s (1995) Pairwise Variability Index was used to quantify prosodic rhythm in the Spanish and the English of community members across generations in order to: (1) assess differences between contact and non-contact varieties of Spanish, (2) investigate the cross-generational stability of prosodic rhythm in the community, and (3) ascertain the type of influence from English, if any, on Spanish prosody. Findings show that while the oldest generations maintain separate systems of rhythm in Spanish and English, the youngest generation demonstrates prosodic convergence.