Although extensive research exists on the personal, social, and academic outcomes of community-engaged programs (CEPs), limited research exists on vocabulary learning and students’ perceptions of their own vocabulary learning through participation in a CEP. Likewise, limited research exists on vocabulary learning in mixed-proficiency groups of Spanish second language (L2) learners. This study contributes to the current literature by exploring the vocabulary learning of 57 mixed-proficiency L2-Spanish college students who participated in a health-focused after-school program with Spanish–English bilingual children in a Midwestern city in the US. The higher proficiency students were enrolled in a language-focused class, whereas the lower-level students were enrolled in a Spanish for health professional’s class. Student reflective narratives revealed positive perceptions of vocabulary learning during the CEP, as vocabulary learning was seen to be fundamental to connecting with children in the Latino community. Productive vocabulary tests revealed significantly higher gains on vocabulary items that had been explicitly taught in class, but gains varied according to learners’ proficiency levels. Lower-level students showed both higher gains and a higher perception of vocabulary gains than more advanced students. Students’ reflective narratives suggest that the focus on health content in the lower-level class may have contributed both to vocabulary gains and to students’ awareness of learning. Recommendations for effective vocabulary instruction for mixed-proficiency students in a CEP are presented.