The NIEHS-NCATS-UNC DREAM Toxicogenetics Challenge [http://www.niehs.nih.gov/funding/challenges/ ] was announced by Sage Bionetworks [http://sagebase.org<http://sagebase.org/><http://www.niehs.nih.gov/funding/challenges/%20]%20was%20announced%20by%20Sage%20Bionetworks%20[http://sagebase.org<http://sagebase.org/>>] on June 11. The objective of this three-month Challenge is to build predictive models of cytotoxicity based on data obtained from in vitro studies in which lymphoblastoid cell lines derived from 884 individuals were exposed to 156 environmental toxicants and drugs. This computational Challenge aims to engage diverse communities of scientists in competitively solving one or both of two related subchallenges. In subchallenge 1, participants are asked to model interindividual variability in cytotoxicity based on genomic profiles in order to predict cytotoxicity in unknown individuals. In subchallenge 2, participants are asked to predict population-level parameters of cytotoxicity across chemicals based on structural attributes of compounds in order to predict median cytotoxicity and mean variance in toxicity for unknown compounds. Interested individuals can sign up to participate. The Challenge closes on September 15, 2013, and the top-scoring team(s) will be announced in November 2013. The winner of each subchallenge will be invited to speak at the 2013 DREAM conference to be held on November 8-12 in Toronto, Canada in conjunction with the Sixth Annual RECOMB/ISCB Conference on Regulatory and Systems Genomics. Kristie Sullivan Secretary, ASCCT www.ascctox.org<http://www.ascctox.org>