For many of us a museum is a place to visit and see collections of things. Whatever else is on offer, the collections are at the museum’s heart. However, they do not grow by themselves. The objects have to be selected, arranged, labelled and displayed. A disordered clutter is not a museum; nor is a private collection if only its creator can view it. The Science Museum’s collections have grown over the years in response to the cultures it has lived through. This process of growth and change is seldom thought about by a museum’s users, but it has an impact on how we see the museum and interact with it. Here we look behind the scenes to find out how the Science Museum and its staff have met the challenge of preservation and display of our heritage of science and technology.