Southern California public safety agencies, community groups, residents and Mayor Antonio Villaraigosa will be among the participants in Tuesday's 25th annual National Night Out.
There are block parties, barbecues and marches planned in L.A. and Orange County.
Organizers say they want to promote neighborhood spirit and partnerships between police and community groups against crime and drugs.
Villaraigosa is scheduled to join Los Angeles Police Department Chief William Bratton and Councilman Dennis Zine at the West Valley Division's National Night Out event at Warner Center Park in Woodland Hills.
Los Angeles County Supervisor Yvonne Brathwaite Burke will preside over an event at Leon H. Washington Park celebrating the graduation of participants in a Florence-Firestone area youth leadership program.
Both events are set to begin at 5:30 p.m.