This chapter begins by considering what is meant by scientific literacy and how the PISA 2006 scientific competencies encompass basic components of scientific literacy. Then it describes some examples of how these competencies are assessed in PISA 2006 and how they can be used in classroom assessment. The chapter concludes with some recommendations on how teachers can use PISA 2006 scientific competencies to foster the development of knowledge, skills, and attitudes that, when considered together, provide some insight into their students' scientific literacy.