Considerable interest has recently mounted regarding the biological roles of Gram-negative outer membrane vesicles (MVs). The first discovery of MVs was made over four decades ago, and it is now clear that most Gram-negative bacteria produce MVs, with Pseudomonas aeruginosa and Escherichia coli as the most extensively studied. Much of our knowledge of the biological roles of MVs and mechanism of MV formation is due to T.J. Beveridge and colleagues. Beveridge pioneered the field of MV research not only by enhancing our understanding of MV function, but also through the application of a wide variety of physical, chemical, and genetic techniques to complement his elegant electron microscopy investigations. Here we review the contributions of Beveridge's group to our understanding of MV biology.