This study analyzes the nature of spontaneous bilingual peer interactions across Spanish/English integrated learning contexts, as well as the roles played by Spanish-dominant and English-dominant peers in mediating each others' bilingual, biliteracy, and cross-cultural learning in a two-way partial immersion (TWpI) program. Implications for designing and implementing effective language, literacy, and cross-cultural learning environments for bilingual children from minority- and majority-language backgrounds are addressed. (Contains 2 footnotes and 1 table.)