In an era of increasingly common and detailed imaging of the thorax, thoracic aortic aneurysms are being discovered in their precomplicated state with increasing frequency. At the same time, the list of potential treatments for thoracic aneurysms is beginning to expand. Deciding which treatment method to employ and which aneurysm to treat is often difficult. The risk of aneurysm complications must be balanced against the risks of the treatment. This work explores the behavior of thoracic aneurysms, the state-of-the-art in treatment, and a rational approach to the treatment decision is proposed.