Intracellular trafficking of membrane-coated vesicles represents a fundamental process that controls the architecture of different intracellular compartments and communication between the cell and its environment. Major trafficking pathways consist of an inward flux of endocytic vesicles from the plasma membrane and an outward flux of exocytic vesicles to the plasma membrane. This overview describes a number of molecular biology tools commonly used to analyze endocytic and exocytic pathways. The overall emphasis is on major proteins responsible for vesicle formation, recognition, and fusion. These include components of vesicle coats, adaptor complexes, SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins, and Rab guanosine 5'-triphosphatases (GTPases), which represent attractive targets for genetic manipulation aimed at unraveling mechanisms of endocytosis and exocytosis.