The girls first stopped off at Barnes and Noble for a signing.
“Biggest signing ever?! Fire Marshall wanted to shut it down?! Ahhh so excited,” Kylie tweeted.
Kendall added, “just got done signing 1,100 magazines! thank you to everyone who came!”
After the signing, Kylie and Kendall headed over to the W Hotel Westwood in Beverly Hills where they celebrated with friends, family and other stars.
FYI: Kylie wore a d.RA lace dress to the party and a burgundy French Connection Sub Silky Tie Top, paired with an Isabel Marant skirt for the signing.
20+ pics inside…