Literacy in the Middle (LIM) is a sixth- through eighth-grade literacy initiative being implemented in the Houston Independent School District (HISD). The initiative is an extension of the Literacy by 3 initiative being implemented at the elementary school level, district-wide. LIM focuses on literacy across the curriculum, including the core content areas of science, math, and social studies using reading, writing, speaking/listening, and thinking domains. This report highlights the implementation of LIM and its effect on reading and math performance and growth of middle school students. The implementation involved summer and year-long professional development for teachers. A teacher survey, repeated-measures design, regression, and descriptive analyses were used to evaluate the implementation and effects of LIM.