Mathematical communication has been an important feature of standards documents since National Council of Teachers of Mathematics’ (NCTM) (1989) Curriculum and Evaluation Standards. Such an emphasis has influenced content standards of states from then to present. This study examined how effective the prevalence of various forms of mathematical communication in 2009 state standards documents was in regard to National Assessment of Educational Progress (NAEP) 2009 achievement scores for Grade 4. Analysis suggests mixed results with potential implications as states move toward fully implementing the Common Core State Standards in Mathematics. Specifically, although including language requiring mathematical descriptions from students had a positive effect on Grade 4 NAEP 2009 achievement scores, including language requiring rationales and justifications was not found to have a statistically significant effect.