Music cognition depends on the existence and deployment of processes for detecting, storing and organizing musical materials according to underlying structural features. Common cultural experiences develop these processes to a certain degree, but specifically designed and supported learning environments are required to achieve the levels of expertise required to perform western art music. Certain motivational and social factors are therefore implicated in the maintenance of activities that promote skill-acquisition, such as practice. Expert musical performance is not just a matter of technical motor skill, it also requires the ability to generate expressively different performances of the same piece of music according to the nature of intended structural and emotional communication. This review examines these abilities and describes how some of them have been shown to have lawful relationships to objective musical and extra-musical parameters. Psychological research is thus engaged in a process of demystifying musical expertise, a process that helps to improve upon culturally prevalent, but ultimately non-explanatory, notions of inborn 'talent'.