This paper deals with how the natural behavior of animals kept for production can be integrated when planning new housing systems or making changes to existing housing systems. Natural behavior can be defined as the repertoire of different behaviors animals show when kept in environments where they can carry out behaviors created in the evolutionary process. Motivation and innate behaviors are important aspects of natural behavior, and hindering them may lead to abnormal behavior and stress. One should first get a basic knowledge about the species-specific behavior in the wild or a seminatural environment. Thereafter, key stimuli and key features for normal behavior should be worked out, where after a reduction in space, development of a pen, scientific testing, modification, and finally testing the function in a larger scale should be carried out. Examples of housing of calves during the milk period and housing of sows around farrowing are given.