Research on bilingual education overwhelmingly shows that bilingual programs supporting the first language of emerging bilingual students ultimately leads to their academic success in both languages. Yet it is because of the variety of programs, inconsistencies in program labeling, and differing levels of implementation of different programs that discrepancies in bilingual education outcomes surface. Because of such varying findings in the research, when evaluating a bilingual program, investigating its level of implementation within schools is of utmost importance, as varying levels of implementation can lead to varying levels of success. The purposes of this mixed methods study were to examine the fidelity of implementation of an innovative bilingual intervention entitled Literacy SquaredRTM, to investigate the connection between teacher implementation and classroom outcomes, and to assess the utility of an observation matrix created to determine program implementation levels. In order to investigate the implementation of Literacy Squared, case studies were conducted in six first through third grade classrooms at two schools. Data were collected through classroom observations and teacher interviews, and the collection of lesson plans, artifacts, and student outcomes. Findings from this study illustrate that implementation levels differed by classroom, and while high and low implementers were present at each school, neither school had consistent implementation. Furthermore, a category of developing implementer emerged for an inexperienced, unlicensed teacher who was still developing her teaching style and beliefs, but attempting to implement the intervention to the best of her ability. Barriers to teachers' implementation included a lack of time and too many programs within schools. Teachers who already possessed characteristics of effective teachers were able to overcome barriers and integrate the Literacy Squared intervention into their classrooms, but teachers who struggled with daily routines, planning, and classroom management, could not. Teachers' implementation levels were connected to classroom outcomes on informal Spanish and English reading and writing assessments and a high-stakes test. The observation matrix was found to be helpful in examining fidelity of implementation, though refinements are needed before its reliability and validity can be established. Findings have implications for program implementation, implementation of Literacy Squared, and bilingual education in general.