Criminal Justice, Criminology, Penology and Security are new disciplines taught in Kenyan Universities and Colleges with no specific textbook readily available to students and practitioners. This is the first introductory textbook dealing exclusively with National Police in Kenya and provides useful information about the workings of the Police in Kenyan context. It is useful to Police officers, Children Officers, and students taking Certificate, Diploma and Degree courses in Criminology, Criminal Justice, Penology, Sociology, Social Work and legal Studies with pertinent information in Police. It has a concise explanation of the origin, development of departments, Organizations, Structures and workings of the Police agency in Kenya. The writers have paid special emphasis to the Kenyan reforms taking place within the Criminal Justice agencies.The text has incorporated provisions of the New Constitution of Kenya 2010 in relation to Kenya Police Service.New Special topic of Community Policing,Oversight Authority and how they control the behaviour of the Police Service in Kenya,Kiswahili version of the Constitution have been incorporated for easy reference by non Kiswahili readers.