Results from external studies often play an important role in many aspects of a clinical trial. Their incorporation into the decision making process of a trial, however, is rarely conducted in a formal manner. This conference will address what formal role, if any, meta-analytic summaries of external results should have in the design and monitoring of an ongoing trial. This introductory presentation describes in detail the example from obstetric research which motivated the conference topic, and, in a Bayesian framework, summarizes the general implications of formally incorporating meta-analytic results into the design and analysis of a new trial.