The identification of potential new therapeutic agents is met with significant challenges in preclinical discovery and development. Both efficacy and safety endpoints must be adequately assessed prior to testing a new investigational agent in humans. Perhaps the most challenging part of drug discovery is the mitigation of safety risks that arise during most drug discovery optimization efforts. In order to design and make safer drug candidates, medicinal chemists work with cross-functional drug discovery partners to understand, assess and mitigate safety risks associated with potential new drug candidates. Successful drug discovery teams will properly design and execute experiments that can best assess and discharge risks prior to the first human dose (FHD). This must be accomplished in the context of anticipated human drug exposures and patient risk-benefit analysis. Through the lens of modern medicinal chemistry, this course explores the current best practices and methods used to identify, understand and mitigate common preclinical safety risks from both a strategic and tactical perspective. Importantly, the course also describes proactive approaches that can help medicinal chemists avoid many safety issues and deliver safer small molecule drug candidates. A key objective of the course is to improve medicinal chemist’s preparedness for participation and leadership on cross-functional drug discovery teams.