Siblings play a critical role in the socialization experiences of their younger siblings. Societal values, standards, and customs are transmitted and created through the process of modeling and the construction of shared meaning. It follows, therefore, that the process of socialization may be culturally dependent. Using multiple case studies of five sibling dyads, we aim to examine the process of initiation and co-construction of second-generation Spanish-speaking children while engaged in free play activities. Examination of fieldnotes, videotapes, and transcriptions suggests that younger siblings initiated more interactions than their older siblings. However, older sibling initiations were more likely to lead to co-construction. Moreover, when younger sibling initiations were successful, this process of co-construction appears to be contingent on the support provided by their more skilled older siblings. We suggest that by serving as models, older siblings are fulfilling their familial responsibility and preparing their younger siblings for school-based social interactions.