Does the macro's name describe what the macro generates (e.g. BOOST_XYZ_EXPRESSION) or does the macro's name describe a purpose (e.g. BOOST_REGISTER_XYZ)? Name describes expansion : semicolon must not be added by the user Name describes purpose : semicolon must be added by the user It indirectly depends on the design of the particular library: If you want the user to look at the macro as part of the interface use "purpose naming" (imperative) and have the user supply a semicolon. If you want the user to look at the macro as a code generator (e.g. convenience-shortcuts with a documented alternative that could be written manually) use "expansion naming" (noun/perfect) and put the semicolon inside the macro. Regards, Tobias