Liver-directed therapies for unresectable cancers in the liver are evolving with increased efficacy and decreasing toxicity. One of these approaches uses radioactive microspheres delivered to hepatic tumors via the hepatic artery system-radioembolization. Use of this therapy is rapidly increasing worldwide with over 20,000 patients treated thus far. Therefore, greater understanding of its potential and optimal positioning of this therapy in the multimodality management of cancers affecting the liver is needed. This task has been undertaken by a group of the most experienced clinicians in radioembolization from multiple disciplines involved in this therapy.