The Molecular Screening Shared Resource provides Cancer Center members with state-of-the-art high-throughput screening capabilities of shRNA and small molecule libraries to identify genes and tool inhibitors of candidate therapeutic targets. Identifying drug-like, small molecules that regulate the activity of therapeutic targets holds promise in defining new treatment paradigms, especially for recalcitrant tumor types, where current clinical practice is suboptimal. In the 2008 submission of the Wistar Cancer Center Support Grant, the services of this Resource were incorporated into the Protein Expression and Libraries Shared Resource. Backed by an investment of over $1 million, the Resource has grown steadily in instrumentation capabilities, range of services and scientific impact for a broad spectrum of research projects. Currently, the Resource offers: 1) biochemical-, cell-, and high-content based assays amenable to high-throughput screening in 384 well microtiter plates; 2) managing of libraries of small molecules; 3) high-throughput screening of small molecule libraries; 4) analysis of biological and chemistry datasets; 4) characterization of potency and selectivity of newly identified compounds in secondary, orthogonal assays. These services are provided through a centralized laboratory equipped with robotics, libraries of drug-like molecules arrayed in high-density microplate formats, and computational infrastructure for efficient analysis, interpretation, and management of biological and chemistry datasets. The Resource is operated by an experienced Managing Director and dedicated laboratory staff, cross-trained in all services offered. This allows for timely project management, quality assurance, and dissemination/integration of data critical for translation of basic biological observations into potential therapeutic strategies. As a result of this technical expansion, growth of user base, and integration of services, the Resource is now presented as a stand-alone Cancer Center Shared Resource, and operationally classified as a Type II Resource to reflect the highly specialized, frequently collaborative nature of most services. Through its activity over the last project period, the Molecular Screening Resource has enabled dissection of complex signaling pathways of tumor onset and progression, validation of anticancer agent(s), and proof of concept results that were ultimately incorporated into early phase clinical trials. As an engine for multidisciplinary research collaboration, the Resource has contributed to critical publications and grant funding across all three Cancer Center Programs.