Baby marmoset monkeys for adoption. Marmosets are very small monkeys (about the size of a coke can) and weigh about one pound full grown. These babies wear clothes and diapers and are just as cute as can be. Marmosets are good "starter monkeys" They are all the fun of a big monkey. They will make very affectionate entertaining pets. We are a small USDA licensed breeder and our babies get the care they need to get off to a good start. If you are looking for a monkey to add to your family, then contact us right away.