Multidimensional gas chromatography (MDGC) involving multiple GC separation stages has in recent decades been significantly extended beyond the classical heart-cut (H/C) MDGC method, where a single or few zones of eluate from a first column are sampled into a second column. While this target method is still of use for such examples as enantioselective analysis of a small number of compounds, a method which applies a two-column separation mode in an untargeted or profiling manner has become of substantial interest to general essential oil/flavour/fragrance analysis. This effectively describes a comprehensive two-dimensional GC (GC × GC) technique, in which greater peak capacity, improved component detectability and limits of detection, separation from underlying interferences, and likelihood of measurement of a single compound mass spectrum in GC × GC–mass spectrometry (MS) is now achieved when a well-designed GC × GC method is implemented. This chapter introduces the rationale for developing MDGC methods, and outlines a variety of MDGC approaches incorporating two or more capillary GC columns. Detection with a number of different MS techniques is considered. Olfactometry in conjunction with MDGC is described, and approaches to enantioselective analysis are described. Application to essential oils, flavours and fragrances are presented.