Small cell lung cancer (SCLC) is the most frequent cancer histology associated with paraneoplastic syndromes. These syndromes are typically caused by ectopic hormone production or immune-mediated tissue destruction caused by neural antigen expression from cancer cells. This antigen expression induces the production of antibodies that cross-react with neural tissue. This article discusses the most common ectopic hormone and neurologic paraneoplastic syndromes and emphasizes the relationships among antigens, clinical syndromes, and outcomes. Although ectopic hormone production has been associated with extensive-stage disease and a poorer outcome, the antibody-mediated paraneoplastic syndromes are prognostic factors associated with more favorable outcomes. Both have the potential for improvement with cancer treatment.