This book presents the reader with an understanding of the role played by matrix metalloproteinases (MMPs) in the normal and diseased central nervous system (CNS). These enzymes may be important to brain development, and may also contribute to tissue destruction, which is observed with inflammatory and degenerative conditions of the brain. The book provides a background on the biology of MMPs, and on the stimuli and conditions that are linked to an increase in their production and activity. It describes the targets of MMPs, which include matrix proteins such as collagen, soluble cytokines and chemokines, and cell surface receptors. Studies implicating MMPs in neuronal process outgrowth and cell migration in CNS development are covered. The book also touches on studies suggesting that, in certain situations, dysregulated MMP activity and/or production may be critical to blood–brain barrier breakdown and neuronal damage.