PISA, the OECD's international program of assessment of reading, scientific and mathematical literacy, aims to assess the knowledge and skills that students have acquired at school and their ability to use them in everyday tasks and challenges. It also uses questionnaires to gather data on students' attitudes to learning and the conditions of schooling. Since 2000, PISA has tested the scientific and mathematical literacy of 15 year old students from around the world. By 2009 there are over 70 participating countries. This paper describes the design of the PISA assessments, discusses mathematical and scientific literacy and reports on a selection of results from the PISA assessments, associated surveys and related analyses to give a flavour of the information that has resulted from this major international initiative. (Contains 1 figure and 2 notes.)