This chapter represents a modest attempt to begin answering the question of what we can learn from national data to better inform literacy policy. However, in order to answer that question, there is a need to understand (1) practical issues and limitations of collecting national literacy data and (2) the infiuence of the dominant ideology of monolingualism on the framing of national data questions. The rst part of this chapter addresses the practical concerns and limitations with reference to the National Adult Literacy Survey (NALS) and the National Assessment of Adult Literacy (NAAL). The second part addresses the ideological assumptions underlining the U.S. Census and how some of the census data help refute and better inform those assumptions. The chapter concludes that a more robust focus on language diversity and literacy in other languages is needed to better inform adult literacy policy.