As of the census of 2000, there were 20,318 people, 6,823 households, and 5,690 families residing in the city. The population density was 906.9/km² (2,348.9/mi²). There were 6,989 housing units at an average density of 312.0/km² (808.0/mi²). The racial makeup of the city was 65.53% White, 0.36% Black or African American, 0.18% Native American, 31.57% Asian, 0.04% Pacific Islander, 1.01% from other races, and 3.31% from two or more races. 4.80% of the population was Hispanic or Latino of any race.
There were 6,823 households out of which 44.1% had children under the age of 18 living with them, 73.7% were married couples living together, 7.3% had a female householder with no husband present, and 16.6% were non-families. 14.4% of all households were made up of individuals and 8.0% had someone living alone who was 65 years of age or older. The average household size was 2.95 and the average family size was 3.27.
In the city the population was spread out with 29.8% under the age of 18, 5.1% from 18 to 24, 20.9% from 25 to 44, 30.2% from 45 to 64, and 14.0% who were 65 years of age or older. The median age was 42 years. For every 100 females there were 93.1 males. For every 100 females age 18 and over, there were 90.5 males.
According to a 2007 estimate, the median income for a household in the city was $128,113, and the median income for a family was $154,854. This makes La Canada Flintridge the 18th most affluent city in the United States of America, according to www.forbes.com Males had a median income of $92,760 versus $57,321 for females. The per capita income for the city was $52,838. About 3.6% of families and 4.3% of the population were below the poverty line, including 4.8% of those under age 18 and 5.1% of those age 65 or over.
La Cañada Flintridge has been home to many celebrities over the years, including Mark Geragos; Ron Howard; Haley Joel Osment; his sister, Emily Osment; Kevin Costner; Miley Cyrus and her father, country singer Billy Ray Cyrus who have since moved to Toluca Lake. Three of Walt Disney's top animators, Frank Thomas, Ollie Johnston and Eric Larson settled here. Currently several prominent animators and TV news personalities make La Cañada Flintridge their home. It is also a popular filming location, where parts of movies such as "American Pie," "Date Movie," "Old School" and the 1946 Frank Capra / James Stewart (actor) holiday classic "It's a Wonderful Life" have been shot. La Cañada Flintridge is also the home of current MLB infielder Rafael Furcal, as well as former MLB pitcher Jae Seo.