It is likely that most orthopedic surgeons will see a patient with a benign or a malignant musculoskeletal tumor sometime during their career. However, because of the rarity of these entities, many surgeons may benefit from a review of how to evaluate a patient with a bone lesion or a soft-tissue mass. A logical approach is necessary for the evaluation of imaging studies as well as in the workup of children and adults with a possible tumor. It is important to have a good working relationship with a musculoskeletal radiologist to assist in interpreting the images. If the treatment algorithms lead to a conclusive diagnosis of a benign bone tumor, benign soft-tissue mass, or metastatic bone disease, the orthopedic surgeon may choose to definitively treat the patient. If the workup indicates an indeterminate lesion, it may be prudent to discuss the situation with an orthopedic oncologist or transfer the care of the patient to a physician with more specialized knowledge. A careful, logical workup is needed before surgery to limit risks to the patient and optimize the chances for a favorable outcome.