This chapter focuses on the meaning, patterns and development of human behaviour. From a developmental point of view, the first experiences in communication are all to do with behaviour. Margaret Yelloly, writing in 'Behaviour Modification in Social Work' stresses the need for establishing a relationship which will enable to explore his problem. All societies seem to have unwritten rules about physical closeness which apply in different situations and with different groups of people. Within any class or geographical grouping some people find any form of physical contact difficult, and others use physical contact regularly and spontaneously as part of their communicating. An inner fantasy world of the serious mentally ill personality influences their perception of reality that the actual behaviour of others is transformed into something different and therefore as such does not affect the individual.