NCIS: Los Angeles (Naval Criminal Investigative Service: Los Angeles) is an American television series combining elements of the military drama and police procedural genres, which premiered on the CBS network on September 22, 2009.^[3] In the USA, the series airs following NCIS on Tuesdays.^[4]

NCIS: Los Angeles is the first spin-off of the successful NCIS,^{[5][6][7][8][9]} which itself was a spinoff of another CBS series, JAG. On October 7, 2009, CBS gave the series a full-season pickup, extending the first season to 22 episodes.^[10][11][12] The season was extended again on November 4, 2009, when CBS announced its order for an additional two episodes.^[13]

The second season began airing on September 21, 2010.^[14] On May 18, 2011, CBS renewed the series for a third season.^[15] On August 18, 2011, CBS announced that the series would crossover with Hawaii Five-0, by having Daniela Ruah guest star as Kensi Blye on the latter series.^[16] On January 11, 2012, CBS announced that the series would do a secondcrossover with Hawaii Five-0 by having Daniel Dae Kim and Scott Caan guest star on an episode in May.^[17] On March 14, 2012, CBS renewed NCIS Los Angeles for a fourth season.^[18]