Cleaning is more than just removing dust and dirt, it is an intervention in the manner of living of people. In state correctional institutions for youths, cleaning used to be a part of the correction and rehabilitation program; it prepared the juveniles for a profession in society. A variation on the question of whether some place is dirty, is: when is something clean? The answer depends on factors, a number of which are quite subjective. Clean means different things in different places. Cleanliness is a mixture of impressions: how it smells, feels, and looks. As it is dependent on the situation, it should be discussed and defined in a plan. The plan must be clear both to the museum employee and the (often nonnative) cleaner. This requires communication and training. The instruction to the cleaner involves a description of the building, its history and materials, a description of the use of the building, the type of work and the employees, and an explanation of the collection or the presented exhibits. The concept of safe cleaning must be explained. Safe means safe for the visitor (floors must not be slippery) and safe for the building and the objects. Furniture can be chosen of a type so as to facilitate cleaning; legs of cupboards and cabinets must be sufficiently high (e.g., 15 cm) for cleaning underneath. The performance of the cleaners will benefit from a clear appraisal of their work. They should do their work as much as possible as an integral part of the work of all employees.