With the increase in emergent bilinguals and higher standards for all, the challenge for educational stakeholders is to fully utilize dual language programs as a prominent means toward meeting and surpassing rigorous state and national standards. Part of maximizing dual language programs’ impact, and the purpose of this study, was to provide detailed analyses of program models and student biliteracy development. Thus, the research questions sought to explore the level of understanding and implementation of dual language programs in general and the biliteracy component in particular at each campus, before documenting the second through fifth grade English and Spanish reading biliteracy trajectories of students at each school. Both campuses experienced more challenges in the implementation of the program structure, staff quality, and professional development rather than in curriculum and instruction. Furthermore, although both campuses’ students experienced positive trajectories towards biliteracy by the end of fifth grade, each campus was characterized by different rates and correlation between English and Spanish reading growth in each grade. Finally, the researcher conducted a split plot MANOVA to examine how much variance in the biliteracy trajectories was explained by school attendance, gender, initial English oral language and initial Spanish oral language; only school of attendance …