Bacterial meningitis is a life-threatening infectious disease with high mortality and disability rates, despite availability of antibiotics and adjunctive therapy with dexamethasone. Several risk factors and predisposing conditions have been identified that increase susceptibility for bacterial meningitis. Such risk factors can consist of medical conditions resulting in immunodeficiency, host genetic factors or anatomical defects of the natural barriers of the central nervous system. These factors can increase the risk of meningitis in general or result in a specific risk of meningococcal or pneumococcal meningitis, the two most important causes of bacterial meningitis, which are characterized by distinct host–pathogen interactions. In this review we describe several risk factors for community-acquired bacterial meningitis in adults and discuss what preventive measures can be taken in these populations.