The first study looked at the relative contribution of domestic violence to the assault or injury of police officers. Calls involving mentally deranged people, handling prisoners, and other arrests were more likely to result in the assault or injury of police officers than domestic violence calls. The second study evaluated the conduct of undercover investigations by 89 police departments in large U.S. cities. All 89 police departments said they conducted undercover operations, primarily to investigate drug offenses; 64 had implemented guidelines for undercover operations. The third study examined both specific and general citizen attitudes toward the police in a midwestern city. Specific attitudes tended to be more favorable than general attitudes, and global attitudes affected specific attitudes. The fourth study looked at whether citizen demeanor affected police discretion in arrest decisions. Overall, demeanor and certain demographic variables had an effect on the likelihood of arrest. Different measures of citizen demeanor, however, influenced the extent to which demeanor had an effect on the likelihood of arrest.