ABSTRACT: The presence of undetected impurities in drug products can lead to devastating side effects. For example, Diethylene Glycol (DEG) as an impurity has troubled the drug product industry for nearly 75 years. DEG has been used as a low cost but toxic substitute for glycerin and has directly caused the death of hundreds of children and adults. Tragedies such as these are preventable. The scope of this presentation is to discuss a scientific, collaborative and unbiased approach to the responsible evaluation of pharmaceutical ingredients. The evaluation must begin internally and extend to the outer boundaries of a drug product’s supply chain. A weak approach to the evaluation of ingredient impurities can potentially adulterate the entire chain. Investigation of possible impurities begins with a realistic evaluation of a firm’s manufacturing environment including historical factors and inherent properties of the product and its raw materials. Furthermore, the investigation must include in depth evaluations of raw material manufacturing paths and supplier questionnaires. These factors must be compiled to design a comprehensive impurity profile that, when combined with proper analytical techniques, supports industry’s assurance of patient safety.