L’Oréal haircolor advertised that it’s a little more expensive, but, according to its famous catchphrase, “I’m/You’re/We’re worth it.” “Because I’m worth it” was trademarked with a first use date of March 5, 1973, “Because you’re worth it” was trademarked with a first use date of October 17, 1975, and “Because we’re worth it, too!” was trademarked with a first use date of January 1998.
 
Ilon Specht of McCann Erickson is credited with coming up with the slogan.
 
Versions of the slogan had been used earlier. “I’ve Increased Your Salary Because You’re Worth It” (said by a boss) was in a 1930 ad. “Because you’re worth it” was in 1959 ads for a gold paperweight. “Hanes Hosiery & Panty Hose…Because You’re Worth It!” was in an ad in the Lancaster (PA) New Era on December 4, 1972.
 
   
Wikipedia: L’Oréal
L’Oréal S.A. is a French personal care company headquartered in Clichy, Hauts-de-Seine with a registered office in Paris. It is the world’s largest cosmetics company and has developed activities in the field concentrating on hair colour, skin care, sun protection, make-up, perfume, and hair care.
(...)
L’Oréal’s advertising slogan is “Because I’m worth it”. In the mid 2000s, this was replaced by “Because you’re worth it”. In late 2009, the slogan was changed again to “Because we’re worth it” following motivation analysis and work into consumer psychology of Dr. Maxim Titorenko. The shift to “we” was made to create stronger consumer involvement in L’Oréal philosophy and lifestyle and provide more consumer satisfaction with L’Oréal products. L’Oréal also owns a Hair and Body products line for kids called L’Oréal Kids, the slogan for which is “Because we’re worth it too”.
           
February 1930, Good Housekeeping (New York, NY), pg. 166, col. 1 ad:
“I Never Expected A Raise So Soon” (Said by a secretary.—ed.)
“I’ve Increased Your Salary Because You’re Worth It” (Said by a boss.—ed.)
(Speedwriting, Inc.—ed.)
   
9 February 1959, Kansas City (MO) Times, pg. 29, col. 5 ad:
“YOUR WEIGHT IN GOLD” 4.00
“Because you’re worth it”...loveliest Valentine thought, to express with this handsome personalized paper weight. 24-K gold-plated
(Harzfeld’s store.—ed.)

19 April 1959, Boston (MA) Sunday Globe, pg. 57, col. 1 ad:
A Specially Nice Gift for Mother
You’re Weight in Gold
BECAUSE YOU’RE WORTH IT.
(Lauriat’s store.—ed.)
       
4 December 1972, Lancaster (PA) New Era, pg. 21, col. 3 ad:
Hanes Hosiery & Panty Hose
...Because You’re Worth It!
 
23 April 1973, Lowell (MA) Sun, Focus sec., ‘Let’s have it for Vanity!,” pg. 7, col. 5-6:
But the new thing is VANITY. There’s this group of gorgeous gals, all of whom color their hair with something which, they boast, is the most expensive hair-coloring around. But the cost be hanged! ... because, “I’m worth it!” each of them says proudly. What this does is make you feel awfully shortchanged if YOU never have found occasion to splurge, and then announce it is your DUE.
 
21 December 1973, The Daily Advertiser (Lafayette, LA), pg. 11, col. 2 ad:
Why buy the most expensive haircolor in the world?
Because you’re worth it.
(L’Oréal.—ed.)
 
November 1974, Good Housekeeping (New York, NY), pg. 200, col. 1 ad:
Once you’ve tried it, you’ll never settle for anything less than L’Oréal. Because you’re worth it.
 
9 January 1975, New York (NY) Times, “L’Oreal Sponsors Network Show,” pg. 57, col. 4:
L’Oreal, which makes hair coloring for women, will be a sponsor for a network television special for the first time tonight.
 
Produced by the NBC News Department, the three-hour-long show, titled “The Changing Roles of Man & Woman,” would seem the perfect vehicle for a company whose only advertised brand uses the theme “Because I’m worth it.”
 
OCLC WorldCat record
Paying for Quality Because You’re Worth It.
Author: Lynne D Meservey
Edition/Format: Article Article : English
Publication: Child Care Information Exchange, n49 p36-37 May 1986
Summary:
Examines the factors involved in the pricing of child care services. (HOD)
           
11 November 1996, Mediaweek (New York, NY), “L’Oreal” by Sean Mehegan, pg. 44:
Agency: McCann-Erickson, N.Y. Begins: Spring Budget: $10 million Media: Cable TV
 
L’Oreal will throw $10 million in television advertising into the 1997 launch of L’Oreal Kids, a haircare line extension that aims to be “the only kids shampoo marketed to kids.”
 
L’Oreal Kids ships next February, with ads breaking in the spring. The company will pitch the product mainly to youngsters ages 3-10 via spots on Nickelodeon, and will likely leverage its famous slogan, “Because you’re worth it” with the new, “We’re worth it- too!”
 
28 March 1997, New York (NY) Times (online), “Carole Cohan, 54, Ad Executive Whose Work Received Awards”:
Among the campaigns she worked on during her two employment periods at the agency were the General Motors car commercials with the theme ‘‘Wouldn’t you really rather own a Buick?’’ the ‘‘Because I’m worth it’’ campaign for L’Oreal hair products, with the actress Cybill Shepherd, and the ‘‘square inch’’ advertisements for Triscuits, the cracker made by Nabisco.
 
OCLC WorldCat record
Because you’re worth it : one hundred years of make-up
Author: Channel Four (Great Britain)
Publisher: [Place of publication not identified] : [publisher not identified], [199-]-
Edition/Format:   Computer file : English
Summary:
History shows us that, despite adversities such as war, economic depression and extreme social change, the desire to look good remains constant. Created as part of a large online resource of Channel 4 history programs, this Web site invites visitors to learn more about the history and evolution of make-up. Trace the relationship between the changing needs of women and of one of the biggest and most influential industries in the world. 
   
OCLC WorldCat record
Because you’re worth it : [100 years of makeup]. Pt. 2 (of 2)
Author: Pip Banyard
Publisher: [U.K.] : Channel 4, 2002.
Edition/Format:   Video : Videocassette   Visual material : English
Summary:
Second of two programmes looking at the birth of the modern cosmetics industry and the stories behind some of its most famous names
 
OCLC WorldCat record
Because I’m worth it. (Gossip Girl novel, #4.)
Author: Cecily Von Ziegesar
Publisher: New York : Little, Brown, ©2003.
Series: Gossip Girl novel, 4.
Edition/Format:   Print book : Fiction : Secondary (senior high) school : English
 
OCLC WorldCat record
Because I’m worth it.
Author: L’Oréal (Firm); Chelsea Art Museum (New York, N. Y.)
Publisher: New York, NY : Assouline Publishing, 2004.
Edition/Format:   Print book : English
         
YouTube
Loreal, because I’m worth it.
rchcc122
Published on Jul 6, 2010
So, this past weekend I was at Anime Expo and had the most fun I’ve ever had at any AX. The cosplayers this year were SO amazing!
     
14 November 2011, Wall Street Journal (New York, NY), “Is L’Oréal’s Slogan Still Worth It?” by Christina Passariello and Max Colchester (online):
When a young McCann-Erickson copywriter came up with L’Oréal’s famous slogan in 1971, advertising was characterized by snappy catchphrases on billboards and 30-second spots. The slogan was a way of wrapping up a story, something that could stick in a shopper’s mind.
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Over the years L’Oréal has changed the slogan to adapt to a changing world. During the 1990s “Because I’m Worth It” became “Because You’re Worth It.” The updated slogan went global in 1997. Preaching to consumers can seem “egotistical and arrogant” though, says Publicis Worldwide’s Ms. Mayer. In an effort to appear more inclusive, L’Oréal altered its slogan 18 months ago to “Because We’re Worth It.”
     
Creative Review (February 2012)
15: L’Oréal (1971) – Because I’m Worth It
Ilon Specht, McCann Erickson
(...)
When a young New York copywriter, Ilon Specht, first created the phrase it ran as ‘Because I’m Worth It’, and was intended to reflect the women’s rights movement of the period.
 
YouTube
The History of “Because You’re Worth It”
L’Oréal Paris USA
Published on Mar 8, 2012
Subscribe to L’Oréal Paris: https://goo.gl/fnguwv
Forty years ago, L’Oréal Paris revolutionized the advertising world with the phrase, “Because I’m Worth It”, spreading the message of respect and recognition for women. Watch this video in honor of International Women’s Day to learn about the evolution of this iconic slogan.
 
Share your “Because I’m Worth It” story with us at: http://www.facebook.com/LoréalParis
 
OCLC WorldCat record
Because You’re Worth It: Women’s daily hair care routines in contemporary Britain
Author: Sabine Hielscher
Edition/Format: Article Article
Publication: Internet Archaeology, n42(2016)
   
Bustle
L’Oreal’s “Because You’re Worth It” Origin Story Is Feminist As Hell
By MARLEN KOMAR
Nov 19 2017
(...)
The year was 1973, and the concept came from an advertising agency on Third Avenue in New York City, from the mind of a 23-year-old copywriter named Ilon Specht.
(...)
She put the woman in the ad front and center instead, a woman unburdened with the search for male approval. The original copy read:
 
“I use the most expensive hair color in the world. Preference, by L’Oreal. It’s not that I care about money. It’s that I care about hair. What’s worth to me is the way my hair feels. It feels good against my neck. Actually, I don’t mind spending more for L’Oreal. Because I’m worth it.”
 
(Trademark)
Word Mark BECAUSE I’M WORTH IT
Goods and Services (EXPIRED) IC 003. US 051. G & S: HAIR COLORING PREPARATIONS. FIRST USE: 19730305. FIRST USE IN COMMERCE: 19730305
Mark Drawing Code (1) TYPED DRAWING
Serial Number 73026057
Filing Date July 3, 1974
Current Basis 1A
Original Filing Basis 1A
Registration Number 1036015
Registration Date March 23, 1976
Owner (REGISTRANT) L’OREAL CORPORATION FRANCE 14 RUE ROYALE PARIS FRANCE
Type of Mark TRADEMARK
Register PRINCIPAL
Affidavit Text SECT 15. SECT 8 (6-YR).
Live/Dead Indicator DEAD
 
(Trademark) 
Word Mark BECAUSE YOU’RE WORTH IT
Goods and Services IC 003. US 051. G & S: HAIR COLORING PREPARATIONS. FIRST USE: 19751017. FIRST USE IN COMMERCE: 19751017
Mark Drawing Code (1) TYPED DRAWING
Serial Number 73070043
Filing Date November 21, 1975
Current Basis 1A
Original Filing Basis 1A
Registration Number 1043925
Registration Date July 20, 1976
Owner (REGISTRANT) L’OREAL CORPORATION FRANCE 14 RUE ROYALE PARIS CEDEX FRANCE 75008
Attorney of Record Dyan Finguerra-DuCharme
Type of Mark TRADEMARK
Register PRINCIPAL
Affidavit Text SECT 15. SECT 8 (6-YR). SECTION 8(10-YR) 20160128.
Renewal 3RD RENEWAL 20160128
Live/Dead Indicator LIVE
 
(Trademark)
Word Mark BECAUSE WE’RE WORTH IT, TOO!
Goods and Services (CANCELLED) IC 003. US 001 004 006 050 051 052. G & S: hair care products, namely, shampoos, conditioners and hair styling preparations. FIRST USE: 19980100. FIRST USE IN COMMERCE: 19980100
Mark Drawing Code (1) TYPED DRAWING
Serial Number 75490175
Filing Date May 22, 1998
Current Basis 1A
Original Filing Basis 1A
Published for Opposition April 27, 1999
Registration Number 2262944
Registration Date July 20, 1999
Owner (REGISTRANT) L’OREAL SOCIETE ANONYME FRANCE 14, rue Royale 75008 Paris FRANCE
Attorney of Record RUSSELL H FALCONER
Prior Registrations 1043925
Type of Mark TRADEMARK
Register PRINCIPAL
Live/Dead Indicator DEAD
Cancellation Date April 22, 2006