Volatile substances interacting with food contact materials (FCMs) can migrate through and from packaging. The mass transfer of migrants from FCMs is influenced by three key parameters, namely the initial concentration of the migrating substance within the packaging (cP,0), the diffusion coefficient(s) of the migrating substance in the packaging material (DP) and the partition coefficient between the food contact polymer and the food (KP,F). Analytical approaches for detecting and quantifying migrating (contaminant) compounds vary according to the objectives. Tests include migration potential tests that focus on the initial concentration of substances within the packaging, specific migration tests for compliance testing (especially for FCMs) and permeation tests to evaluate the behaviour of substances through the packaging material or to characterize the properties of functional barriers. The most prevalent techniques for analysing volatile organic compounds (VOCs) in FCM applications are based on gas chromatography (GC), coupled with either flame ionization detection (FID) or mass spectrometry (MS). Sampling is typically achieved by headspace or liquid (solvent) extraction techniques. This chapter introduces migration and permeation tests, outlines the related sampling methods and analytical techniques and discusses different approaches with a view to characterizing the migration of volatile substances in FCMs.