Neuropsychiatric systemic lupus erythematosus (NPSLE) involves a wide range of peripheral and central nervous system manifestations. These manifestations are complex and their pathophysiology is poorly understood. NPSLE can precede the onset of lupus or occur at any time during its course. The American College of Rheumatology (ACR) developed a standardized nomenclature system providing case definitions for the neuropsychiatric syndromes of systemic lupus erythematosus (SLE) to facilitate and enhance patient classification and reporting requirements in clinical research. Estimates of NPSLE prevalence have ranged widely and most are based on research conducted before the introduction of ACR case definitions. This paper reviews the early experience with the ACR nomenclature use and possible future directions for its improvement. The identification and categorization of the major neuropsychiatric syndromes in SLE using ACR case definitions seems to be adequate, however the mildest and most subjective of the syndromes are the most problematic. Even if the definitions in their present form might have drawbacks the only way forward is further use of ACR nomenclature, pooling data from different populations, and collection of experience as a basis for improvement. The acquisition of normative data for ethnic, age and sex stratification would extend their usefulness.