Order of sources in OS X Calendar In Calendar, you can have several calendar sources, e.g. Google,  iCloud, other.

However these appear to be in alphabetical order, i.e. Google first. When you add a new meeting by clicking on an ics file, it defaults to the first one. How can I change the order (or at least set the default calendar).

Inside a source, e.g. iCloud, you can alter the order of the calendars but you can't do that for iCloud and Google.
Preferences > General > Default Calendar
You can set a single default, or make it default to currently selected.