This study addressed the pressing need to help adolescent English learning and economically disadvantaged student populations succeed in science and close achievement gaps. It reports the results of a two-year professional development initiative implemented at a high-poverty suburban high school in South Texas. We examined how the combination of purposeful planning, innovative academic vocabulary instruction, Saturday school, structured tutoring, and a timely focused review impacted the science achievement of EL and economically disadvantaged high-school students, at-risk of academic failure, on a high-stakes state exam. Difference-in-proportions tests were used to determine if students at the Intervention Campus showed positive achievement gains on a high-stakes state test. Then we analyzed data between schools by comparing high-stakes exam passing rates between the Intervention Campus and a Comparison Campus. This study found statistically significant results which suggest that the initiative was beneficial to the students within the Intervention Campus and showed promising effects when compared against a matched Comparison Campus.