The Booklet entitled "The Science of Marine Protected Areas - Mediterranean Sea" summarizes data from Marine Protected Areas (MPAs) around the world, with a particular emphasis on the Mediterranean Sea. MPAs can be a powerful tool to protect, and possibly restore, the ability of ecosystems to provide benefits (food, oxygen, economic opportunities, recreation, and cultural value, etc.). Globally, there is more than one thousand of MPAs in the Mediterranean, although their collective area, especially for no-take zones, is small. What have we learned from MPAs? The science shows that fully protected, well-designed, well-managed, and well-enforced MPAs can support ecosystem functioning and biodiversity, and, on the other hand, the economy and the culture of the Mediterranean region.