This article presents case studies involving the use of thermal desorption gas chromatography-mass spectrometry to compositionally characterize pharmaceutical packaging materials for potential extractables. Knowledge of potential extractables and leachables early in the product development program allows the project team to make informed decisions, potentially minimizing redevelopment efforts and reducing cost. Case studies include selection of a label for use on a polyethylene bottle, selection of a drug contact surface of a blister packaging system, and selection of a stopper.