Student performance on each of the diploma requirements, except for CAS, is mainly assessed through examinations in May. Other forms of assessment are used to put together a comprehensive picture of a student's progress. These assessments are either internally asssessed by the teacher and moderated by an external examiner (including mathematics portfolios, historical investigations, and oral exercises) or they are guided by a teacher and marked by an external examiner (including extended essays, world literature papers, TOK essays, and musical investigations).

Students earn from 1 (lowest ) to 7 (highest) points based on a combined score of the marks from both internal and external assessments. Thus, a student may earn up to 42 points for performance in each of the six subjects. An additional 3 points may be obtained for work in TOK and the extended essay for a total of 45 points. For more details about the additional points, see the statistics page on Signature's 2008 additional points results.

Generally, 24 points is the minimum required for a diploma. Students who do not fulfill CAS requirements do not earn a diploma. See the Diploma Regulations and amendments for more details about points needed to earn a diploma.

For a detailed analysis of IB assessment practices, see the IBO web article, "Diploma Programme Assessement--Principals and Practice."