Crime in Los Angeles has been a major problem in Southern California and concern for Angelenos since the early 20th century, but LA has been experiencing significant decline in crime since the mid-1990s, and hit a record low in 2007, with 392 homicides. The LAPD makes live crime statistics available on the LAPD crimestats and epolice web site (www.lapdcrimemaps.org). However while most cities in the LA-area have shown a constant decrease of criminal activities over the recent years, some, such as Lancaster, Palmdale and Long Beach have shown some increase in crime in 2008.

In the first half of 2008, LA reports 198 homicides – which corresponds to a rate of 9.6 (per 100,000 population) – a major decrease from 1993, when the all time homicide rate of over 21.1 (per 100,000 population) was reported for the year. This including 15 officer-involved shootings. One OIS led to a SWAT member's death, Randal Simmons, the first in LAPD's history.

Current mayor Antonio Villaraigosa is a member of the Mayors Against Illegal Guns Coalition.

According to a May 2001 Drug Threat Assessment by the National Drug Intelligence Center, LA County is home to 152,000 gang members organised into 1,350 gangs. Among the most infamous are the 18th Street, Mara Salvatrucha, Crips, Bloods and the Surenos street gangs. This has led to the city being referred to as the "Gang Capital of America."

South LA, more widely known as South Central LA, is a notoriously dangerous region of the City of LA which has an extensive history of gang violence, as it gave birth to the Bloods, Crips, 38th Street gang, 18th Street gang, Florencia 13, Mara Salvatrucha and other dangerous gangs. Also, a majority of gang wars in LA take place there, as well as racial violence between African-Americans and Latinos. South LA has steadily declined in crime as crime has spread more throughout the LA County in the early 1990s.

South Central had become a byword for urban decay, its bad reputation spread by movies such as Colors, South Central, Menace II Society, Friday, and in particular, South Central native John Singleton's Boyz N the Hood. The rap group NWA's album Straight Outta Compton and the video game Grand Theft Auto: San Andreas also popularised South Central's bad image.

In 2006, the Morgan Quitno Corporation rated Compton as the most dangerous city in the United States with a population of 75,000 to 99,999, and 4th most dangerous overall. The city is notorious for gang violence, primarily caused by the Bloods, the Crips and Hispanic gangs. Compton's violent reputation was popularised in the late 1980s by the rise to prominence of local gangsta rap groups Compton's Most Wanted and NWA. Since then, "Compton" has become a euphemism for anything ghetto-related or gang-related. A recent rapper from Compton to popularise the city's gang culture is The Game.

Compton has a homicide rate about eight times higher than the national average, most of which are gang killings. Economic conditions and Compton's location as the center of the South LA "ghettos" make crime prevention more difficult. Although crime rates had been falling for years after the crack epidemic of the 1980s and early 1990s, Compton has in recent years witnessed spikes in the rate of violent crime.

Compton had 72 murders in 2005, which is a per capita rate significantly higher than the national average for small cities. Recently in an effort to combat this gun violence the Compton citizens were given the option to hand over their guns to the police, and receive a $100 voucher for various goods. During 2006, Compton has deployed twice as many sheriff deputies and the murder rate has decreased from 22 in four months, to just five. Like parts of LA and Long Beach, Compton is also a hot bed for racial violence between Blacks and Hispanics.