A levels remain the most widely used means of entry to British universities. A full A level is normally a two-year course. In the first year students take AS (Advanced Subsidiary) Levels. The AS Level is a qualification in its own right and is recognised for the purposes of university entry, but it also forms the first part of a full A level. The final year's study, known as A2, represents the second half of the A level course. A full A level is only awarded upon successful completion of AS and A2. The second year alone (A2) does not represent a qualification. Students are encouraged to take up to four or five subjects at AS Level, which are narrowed down to two or three at A2.

A2 levels may require exams at the end of the second year or may follow a modular structure with assessment made at the end of each module. AS levels were introduced for the first time in 2000 with a view to broadening sixth-form studies. In their first year they have attracted much comment and some criticism, based chiefly on the heavy workload placed upon students, the lack of time available for wider activities and university choices and the fact that students now face three consecutive years of major examinations from GCSE to A level. It is not yet clear whether modifications will be made.