In two-way immersion (TWI) models of dual-language education programs, majority language speakers and minority language speakers learn alongside each other with the expectation that they will all become biliterate by the end of the program. Research indicates that students in TWI programs perform at least as well as their peers in English only (EO) programs (Lindholm-Leary, 2006); however, there is limited research regarding sociocultural factors of different programs (TWI or EO) that may impact students. Given that sense of school belongingness (Anderman, 2003) and bicultural identity development (Portes & Rumbaut, 2001) have both been shown to positive effects on students, this study focused upon students' sense of school belongingness and bicultural identity development in EO and TWI schools. As TWI (and other dual language) programs are increasing in popularity throughout the United States, and with a particular emphasis on Southern California, students from two Southern California schools participated in this mixed-methods study. Surveys, open-ended questions, observations, dialogue journals, and photo-elicitation interviews were used to examine the bicultural identity development and sense of school belongingness for 4th through 6th grade students in English-only and TWI programs. Results suggest a quantitative relationship between bicultural identity development and school belongingness for some students, particularly for those with access to TWI education. Qualitative findings reveal complicated similarities and differences in the ways students perceive (bi)cultural identity and school belongingness, as well as multiple ways of actualizing a (bi)cultural identity based upon language and context. This study adds to the limited literature regarding sociocultural factors and impacts of different language programs, and it presents important pedagogical implications related to schooling in general.