Ockham IPS and partners are carrying out a study on indicators for measuring aggression and violence against police officers, fire fighters and extraordinary law enforcement officers (boa's). The study should provide answers to the following questions: what indicators are suitable (in terms of validity, reliability, generalisability and practical feasibility) for gaining more insight into the nature, scale and trends of aggression and violence against police officers, fire fighters and boa's; What are the pros and cons of various indicator; and how could these indicators be used in a sustainable and practical way? Can a weighted index (or indices) of aggression and violence based on a number of suitable indicators contribute to a more nuanced understanding?