This paper provides causal evidence to answer the question, "Does the application of a double dose of literacy instruction in middle school improve student performance on subsequent academic outcomes?" The focus of this paper is on an intervention where the second dose of literacy instruction uses research-based instructional strategies, and shows that this instruction leads to systematic improvement in adolescent reading comprehension. How differences in the fidelity of implementation of this policy may impact the effects of the intervention both at the school-level and in aggregate are examined. This district-designed literacy intervention used 5th-grade scores on the Iowa Test of Basic Skills (ITBS) to determine student eligibility for a double dose of literacy instruction in middle school. Students who scored at the 60th percentile or lower on the ITBS reading test were assigned, by rule, to be eligible for this literacy program. Using a regression-discontinuity design, preliminary findings show that there was a positive aggregate effect of the policy for students who were just eligible for the intervention compared to those who were not. Figures are appended.