Nervous system involvement in systemic lupus erythematosus (SLE) can manifest as a range of neurological and psychiatric features, which are classified using the ACR case definitions for 19 neuropsychiatric syndromes. Approximately one-third of all neuropsychiatric syndromes in patients with SLE are primary manifestations of SLE-related autoimmunity, with seizure disorders, cerebrovascular disease, acute confusional state and neuropathy being the most common. Such primary neuropsychiatric SLE (NPSLE) events are a consequence either of microvasculopathy and thrombosis, or of autoantibodies and inflammatory mediators. Diagnosis of NPSLE requires the exclusion of other causes, and clinical assessment directs the selection of appropriate investigations. These investigations include measurement of autoantibodies, analysis of cerebrospinal fluid, electrophysiological studies, neuropsychological assessment and neuroimaging to evaluate brain structure and function. Treatment involves the management of comorbidities contributing to the neuropsychiatric event, use of symptomatic therapies, and more specific interventions with either anticoagulation or immunosuppressive agents, depending upon the primary immunopathogenetic mechanism. Although the prognosis is variable, studies suggest a more favourable outcome for primary NPSLE manifestations compared with neuropsychiatric events attributable to non-SLE causes.