The discovery and development of a new medicine is a long, complex process, characterized by varying degrees of uncertainty at all stages. In addition to incomplete knowledge about the underlying disease mechanisms, challenges can include uncertain translation from preclinical to clinical phases, high failure rate for molecules during clinical testing, and heterogeneity among patients. Quantitative approaches to pharmacology have recently benefited from the integration of diverse research areas (engineering, biology, chemistry and pharmacology, in addition to others) to solve outstanding problems in drug development. Molecule candidate selection, dosing regimens, clinical trials design and execution, and the identification of patient populations are examples of areas that benefit from quantitative pharmacology. These methodologies can be based on sophisticated computer statistical simulations and mechanistic modeling, and are often carried out within the developing disciplines of pharmacometrics and systems pharmacology. These borrow methods and approaches from many scientific fields in pursuit of a more complete understanding of both pharmacokinetics (what the body does to the drug) and pharmacodynamics (what the drug does to the body) characteristics of a drug molecule. This presentation will provide an overview of the history and application of these approaches, with practical examples in multiple therapeutic areas.