Patients with clinical stage I lung cancer can be considered as arising from three treatment groups: (1) good-risk patients, who are usually treated with lobectomy; (2) high-risk patients, who are usually treated with sublobar (segmental or wedge) resection; and (3) medically inoperable patients, who have traditionally been treated with external beam radiation. Stereotactic body radiation therapy and radiofrequency ablation are two approaches that are gaining increasing popularity for medically inoperable patients. Some have even argued that stereotactic body radiation therapy may be equivalent to lobectomy because of equivalent local control. This assumption is incorrect, because the definitions of local control in the surgical, radiation oncology, and radiology literature are not the same. At best, stereotactic body radiation therapy and radiofrequency ablation can only approximate a wedge resection if it is assumed that 100% tumor destruction has occurred. Lymph node dissection and sampling can also be undertaken at the time of sublobar resection, potentially improving outcomes and allowing identification of unsuspected nodal disease. Despite this, stereotactic body radiation therapy and radiofrequency ablation may be clinically equivalent to sublobar resection for the high-risk patient because of lower procedural morbidity and more rapid return to normal function; however, this has not yet been determined in prospective studies. We review current data on oncologic and secondary outcomes such as morbidity and effect on pulmonary function to help define which therapy is best.