Educational reformers often disagree about how to support students' academic development at the intersection of mathematics and literacy. These disagreements often center on whether the epistemologies undergirding literacy or those underpinning mathematics should take primacy. This chapter will show how current and past attempts to highlight mathematical literacy practices have too often been defined from the standpoint of literacy, rather than mathematics. Based on over a decade of work in mathematical literacy, the authors recommend a specific mathematical literacy practice. They describe the rationale for this mathematical literacy practice from the perspective of both mathematics and literacy. They then use vignettes to outline specific instructional strategies that secondary teachers can use to teach this mathematical literacy practice, providing both a theoretical and a pragmatic view of instruction in mathematical literacy.