The Pathology Core is designed to provide the investigators of the Program Project with expert pathologic evaluation of all soft tissue sarcomas (STS) that present to Memorial Sloan-Kettering Cancer Center. The Core will provide a centralized, comprehensive facility for tissue-based research. The resource will provide tissues and associated data in an equitable and ethical manner, provide professional expertise in histo- and molecular pathology and assist and perform tissue-based experimentation. The human tissues used for research studies are obtained under existing IRB-approved protocols. The specific aims are: 1. To provide consistent, expert pathologic characterization of all STS specimens resected at MSKCC, including a description of gross appearance, histologic type, tumor grade, necrosis, and surgical margins. 2. To supervise the procurement of normal and neoplastic human tissue samples and maintain a bank of frozen sarcoma tissue for special studies conducted under the different projects. This process ensures that adequate amounts of correctly identified and processed tissue reach the appropriate laboratories. 3. To provide expert histologic review for individual projects, including tumor viability and assessment of tumor response to various investigational agents used in different studies, either in post-treated surgical specimens or xenografts. Histologic response assessment to various inhibitors will also be provided for the preclinical in vivo mouse models, as well as histologic expertise for the murine knockout/transgenic models . 4. To assist in performing high-throughput tissue microarray (TMA) and interpreting immunohistochemical (IHC) and in situ hybridization studies (ISH) for validation studies of various microarray projects. An ATA-27 Beecher Automated tissue arrayer will be used to construct TMAs of varying sarcoma types and accompanying normal tissues. Quantitative image analysis of the IHC/ISH results will be performed using an ACIS II (automated cellular imaging system) Chromavision slide scanner tissue arrayer. Assistance with the development of the Clinical Tissue Microarray (ClinTMA) Database by the Bioinformatics Core will be provided, and results will be entered into this database as continuous values. These aims offer a substantial infrastructure to the STS Program Project and allows Core B to provide the required services in a cost effective manner.