This systematic review addressed the following key questions on managing small cell lung cancer (SCLC): the sequence, timing, and dosing characteristics of primary thoracic radiotherapy (TRTx) for limited-stage disease; primary TRTx for extensive-stage disease; effect of prophylactic cranial irradiation (PCI); positron emission tomography (PET) for staging; treatment of mixed histology tumors; surgery; and second-line and subsequent-line treatment for relapsed/progressive disease. The review methods were defined prospectively in a written protocol. We primarily sought randomized controlled trials that compared the interventions of interest. Robust evidence was lacking for all questions except PCI, for which a patient-level metaanalysis showed that PCI improves survival of SCLC patients who achieved complete response after primary therapy from 15.3 to 20.7% (p = 0.01). The case for concurrent over sequential radiation delivery rests largely on a single multicenter trial. Support for early concurrent therapy comes from one multicenter trial, but two other multicenter trials found no advantage. Metaanalysis did not find significant reductions in 2-year and 3-year mortality rates for early TRTx. Favorable results from a single-center trial on TRTx for extensive stage disease need replication in a multicenter setting. Relevant comparative studies were nonexistent for management of mixed histology disease and surgery for early limited SCLC. PET may be more sensitive in detecting extracranial disease than conventional staging modalities, but studies were of poor quality. PCI improves survival among those with a complete remission to primary therapy. A research agenda is needed to optimize the effectiveness of TRTx and its components.