Features specially devoted to schema evolution in the F2 object-oriented database system are presented in this paper. They include a meta-circular and reflective model where primitive operations (create, update, delete) on schema objects form a complete taxonomy of schema changes. All the schema objects of a database are updatable and the consequences of these changes on objects are handled either by the trigger mechanism or by the automatic enforcement of the model invariants. The non-traditional physical storage of objects is particularly well suited to efficiently support schema changes.