Resection of metastases in the lung from a wide range of primary sites has become a routine part of the daily clinical practice of a thoracic surgeon. The European Society of Thoracic Surgeons brought together an international group of surgeons in 2006. The initial intention for this Lung Metastasectomy Working Group was to evaluate the evidence and to generate guidance. It rapidly became clear that although there was great experience in performing this surgery, the belief in its benefit relied on clinical case series and registry reports. Evidence fell well short of Evidence Based Medicine standards and robust guidance could not be produced on this basis. This supplement of the Journal of Thoracic Oncology brings together the findings and conclusions of the group under three headings. The first section covers generic issues such as imaging and the technical aspects of pulmonary metastasectomy. The second deals with specific cancer types in which pulmonary metastasectomy is more frequently performed. The third addresses the way forward to get better evidence for this practice.