This paper examines corporal punishment (CP) by parents including its world-wide prevalence, the cause of CP and its link to familial behaviour patterns. Research in many nations indicates that CP by parents is more prevalent and more severe than most people expect. Over time in the western world, CP by parents and others with responsibility for children has probably decreased, with the major decrease in the most extreme types of violence, physical abuse. However the decrease in less-extreme violence by caretakers such as spanking has been glacial. For example, in the US corporal punishment is almost universal, chronic, often severe and of long duration. The author suggests a major portion of the cause of this pattern is found in the characteristics of society, such as cultural norms that permit or require CP for child misbehaviour. He also notes the important role that legal prohibition plays in ending CP, although this should not involve criminal penalties, but occur in a context where parents are informed and supported to make this change.