Like most major American cities, Chicago has experienced a decline in overall crime since the 1990s. However, in addition to its gangland problems, Chicago historically saw a major rise in violent crime starting in the late 1960s. Murders in the city peaked first in 1974, with 970 murders when the city's population was over three million (resulting in a murder rate of around 29 per 100,000), and again in 1992, with 943 murders when the city had fewer than three million people, resulting in a murder rate of 34 per 100,000. It peaked again in 1993 with 931 murders. Following 1992, the murder count slowly decreased to 705 by 1999; by this time, it had the most murders of any big city in the U.S. After adopting crime-fighting techniques recommended by the New York Police Department and the Los Angeles Police Department in 2004, Chicago recorded 448 homicides, the lowest total since 1965. Nevertheless, this murder rate of 15.65 per 100,000 population is still above the U.S. average.

Chicago has been among the first U.S. cities to build an integrated emergency response center to coordinate the city's response to terrorist attacks, gang violence, and natural disasters. Built in 1995, the center is integrated with over 2000 cameras, a direct link to the National Counterterrorism Center, and communications with all levels of city government. Recently installed anti-crime cameras have been introduced and are capable of pinpointing gunshot sounds, calculating where the shots were fired, and pointing and zooming the cameras in the direction of the shots within a two block radius. Early results show these new cameras to be highly effective in reducing crime. Placed in residential areas, these cameras cause some Chicagoans to feel uneasy about being so closely watched. They have prompted some calls of discrimination since these cameras tend to be prevalent in Black and Latino communities with higher than average crime rates.

The FBI often does not accept crime statistics submitted by the Chicago Police Department, which tallies data differently than other cities. The police record all criminal sexual assaults as opposed to only rape as with other police departments. Aggravated battery is counted along with the standard category of aggravated assault. As a result, Chicago is often omitted from studies like Morgan Quitno's annual "Safest/Most Dangerous City" survey.