It's clear from this snapshot that the dress is obviously beautiful and has us wishing we were that stylish in high school, but Dunham says the dress is special to her for another reason.

"I call it the Sisterhood of the Traveling Dress," Dunham wrote, "because she was so tiny yet somehow this fits everyone."

In another throwback of her grandma, who passed away on July 15, Dunham talks about how her grandma's size could be deceiving.

"That's a lot of strength, all springing forth from one tiny broad," she said of her grandma, who was the mother of three daughters. "We are lucky, humbled to have been present in her last days, full of love and gratitude."

Dunham also paid tribute by posting another, more recent shot of her stylish grandmother, which was shot by Dunham's mother, Laurie Simmons.