The behavioral and psychological symptoms of dementia (BPSD) can have serious debilitating effects on the patient and increase caregiver burden. Investigations into the underlying neuropathology indicate that the serotonergic system may contribute to BPSD. In addition, serotonergic pathways are known to interact extensively with the cholinergic, noradrenergic, GABAergic, and dopaminergic systems. Hence, serotonergic therapies may be used to manipulate other neurotransmitters systems to alleviate BPSD or in combination with agents specific for the other neurotransmitter receptor sites. Neurotransmitter-modulated behaviors and evidence provided by pharmacological interventions are reviewed, focusing primarily on the serotonergic system.