NoteAbilityPro is a professional music notation package for the OS X operating system. Developed by Dr. Keith Hamel at the University of British Columbia, it is easily the most sophisticated music notation software available on any platform. NoteAbility combines both musical intelligence and graphical flexibility in a direct and intuitive graphical user interface. Notate anything from simple melodies to complex avant garde orchestral music, play the score on your MIDI synthesizer or using QuickTime Musical Instruments and print a publishable copy of your score on any OS X-compatible printer.
If you have been frustrated by the awkwardness and inflexibility of other notation programs, or by the time it takes to learn them, then you definitely should have a look at NoteAbilityPro.
The demo version of NoteAbilityPro is a complete working copy of the program with some functions disabled. You are not allowed to save files, copy or export in certain formats, and printing is restricted to the first page only. Just follow the simple installation notes, and the OS X Installer application will ensure that all required files are installed into the correct locations.