By Kelsey Glein
Nov 07, 2014 @ 1:15 pm

Concern for the well-being of others doesn't start and end with the holidays, of course. For the “Shining Stars” story in the December issue of InStyle, we caught up with six famous faces who are shedding light on the spirit of giving throughout the year.

Zac Posen may be known for creating some majorly gorgeous gowns, but the designer is also giving his time and energy to a cause he deems more worthy—raising funds for St. Jude Children's Research Hospital, a pediatric center and a research facility in Memphis, Tenn., dedicated to preventing and treating childhood cancers and other catastrophic diseases.

"When I met the St. Jude's national outreach director, actress Marlo Thomas, I was moved by her passion. She has set incredible goals for herself and for the hospital, and I wanted to use my platform as a designer to help her achieve them," Posen tells Katherine Schwarzenegger in InStyle’s December issue. "Many children are in serious need in this world, and I plan to make it a lifelong pursuit to help their situation. I put on runway shows year-round, and I realized that dedicating certain shows to St. Jude could raise funds to benefit the hospital and its patients."

"I make clothing to make people happy, and I wanted to take that to another level where I was actually making a real difference in people's lives," he shares in the behind-the-scenes video above. "So far, we have raised around $3 million for charity in just a six-month period; it has added a whole other dimension to what I do. But I don't care how it makes me feel—what's important is that it gives a child in need access to lifesaving treatment."

To donate or to learn how to volunteer, visit and follow on Twitter @stjude. Plus, watch Zac Posen's video above to learn more about how he got involved in the cause, and pick up the December issue of InStyle for the full Shining Stars feature, on newsstands and available for digital download Nov. 14.