Paraneoplastic neurologic disorders (PNDs) are rare oncological complications caused by an autoimmune response to an underlying cancer outside of the central nervous system (CNS). PNDs can arise from any type of cancer, though they are more commonly seen in underlying small-cell lung and breast cancer, as well as melanoma. Clinical presentations are diverse and contingent on the foci of immunomodulated disruptions within the CNS. Medical workup is typically comprised of laboratory analyses, such as serum studies, antibody screening, brain imaging, and electrodiagnostic testing. However, in many cases, behavioral or cognitive symptoms present prior to the underlying cancer being known or identified. For this reason, neuropsychologists working in inpatient settings can aid the medical team in differential diagnosis by gathering a good clinical history, conducting bedside assessment, and providing recommendations for management of cognitive and behavioral changes associated with PNDs.