A sentimental look back!

Caitlyn Jenner got more than a little nostalgic when celebrating Kendall Jenner's 21st birthday.

"School, track practice, cheerleading practice, all that carpool! Now my little girl is 21," Caitlyn wrote. "Wow, so proud of you, happy birthday."

MUST SEE: Caitlyn and Kendall Jenner Wore the EXACT Same Dress to the Kanye West Fashion Show!

The newly-minted 21-year-old celebrated her birthday with a star-studded bash and was joined by friends and family alike.

And the sweet family moment brought about some emotional feelings from the 67-year-old reality star.

Check out some more of Caitlyn Jenner's sweet moments with the family below!