Psychiatric illness may be associated with objective or subjective motor disorders. This chapter is chie?y devoted to objective motor disorders, but subjective motor disorders may also occur. It is difficult to classify motor disorders because although clear-cut individual motor signs (such as stereotypies) can be treated as if they were neurological symptoms, it is much more difficult to classify more complicated patterns of behaviour. Nonetheless, motor disorders can be broadly grouped into the following categories: (a) disorders of adaptive movements; (b) disorders of non-adaptive movements; (c) motor speech disturbances; (d) disorders of posture; (e) abnormal complex patterns of behaviour; and (f) movement disorders associated with antipsychotic medication. This chapter explores and explains these different categories of motor disorder in the context of psychiatric illness. The chapter concludes with suggested questions for eliciting specific symptoms in clinical practice, in addition to standard history-taking, mental state examination and physical examination.