Sarcomas form a highly diverse group of rare tumors that are derived from connective tissue. More than 100 different malignant and benign soft tissue neoplasms can be recognized by histologic examination. Few diagnostic markers exist, and the cell of origin for many soft tissue tumors is unknown. The accurate diagnosis of many of these tumors therefore remains a challenge. The study of sarcomas has yielded many insights that can be applied to other neoplasms such as carcinoma. For example, the success of the treatment of gastrointestinal stromal tumor with Imatinib has led to an increased effort to find targeted therapies for other malignancies. Here we describe the known molecular changes in a number of sarcomas and focus on novel scientific approaches that can be expected to lead to improved diagnosis, prognostication, and therapy of sarcoma.