Rihanna Dominates and a Michael Jackson Song Debuts at the iHeartRadio Music Awards

celebrated at the first ever iHeartRadio Music Awards held at the Shrine Auditorium in Los Angeles. Rihanna picked up four wins during the ceremony including Artist of the Year, while Grande nabbed the Young Influencer Award.

also came out to the 2014 iHeartRadio Music Awards, where Williams was honored with the Innovator Award.

were in attendance at the iHeartRadio Music Awards, where Leto's band, Thirty Seconds to Mars, performed. "Our new album is a collision of sight and sound that's different from anything we’ve ever done before," Leto told InStyle. "It’s kind of put us on a different path and shattered a lot of expectations, so we're super excited about that."

were a stylish trio at the Fendi flagship store opening in London.

attended a dinner in honor of Stewart (one of Hollywood's favorite stylists) held at Fendi in Beverly Hills, California.

made their first red carpet appearance together since the birth of their baby boy Otis Alexander last month. The new parents stepped out for the Ms. Foundation Women Of Vision Gala 2014 in New York City.

celebrated at a screening of her new film short Every Mile, Every Mother, hosted by Citizens of Humanity at Soho House in New York City.

arrived at the Los Angeles premiere of her new film God's Pocket, which was presented by Brooks Brothers and Sharper Image. The event was held at LACMA and Purity Vodka cocktails were served. The movie hits theaters May 9, 2014.

hosted the launch of the spring collection for her lifestyle activewear line Fabletics in Los Angeles, where guests enjoyed an outdoor pilates session and a peek at the new pieces.

attended FIT's The Future Of Fashion Runway Show at The Fashion Institute of Technology in New York City, where young designers showed off their collections.

attended The Skeleton Twins premiere at the 57th San Francisco International Film Festival in San Francisco, California. Both Saturday Night Live alums star in the film, which comes out later this year.

supported a good cause in an ICB dress at the Alzheimer's Drug Discovery Foundation 8th Annual Connoisseur's Dinner held in New York City, where all funds raised went to the Clinical Trial of Rasagiline for Alzheimer’s disease.

came out to the Free Arts NYC 15th Annual Art Auction to celebrate her husband Scott Campbell, who was honored at the event. All proceeds from the event benefit the Free Arts NYC’s educational arts mentoring programs for underserved youth and families.

celebrated at the launch of Moss' highly anticipated second collection for Topshop at the brand's Oxford Circus flagship store in London. "This line is as true as it gets to being me," Moss tells InStyle.

attended the 10th Annual TIME 100 Gala held at Lincoln Center in New York City. The actress had much to celebrate, as she was honored with a spot on 2014's list of most influential people by the magazine.

also came out for the TIME 100 Gala, where both artists performed. Underwood and Williams were both named to TIME's 100 most influential people in the world this year.

were a gorgeous pair at the celebration of TIME's 100 most influential people in the world.

sparkled in pieces from the Tiffany & Co. Atlas collection at the Chateau Marmont hotel in Los Angeles, where the jewelry label feted their latest collection.

came out for the 2014 AOL Digital Content NewFront in Brooklyn, New York where they each celebrated projects with The AOL On Network that will premiere later this year.

attended the Colleagues' 26th Annual Spring Luncheon hosted by Oscar de la Renta at the Beverly Wilshire Four Seasons Hotel in Beverly Hills, California.

supported a good cause at TOMS "One Day without Shoes" event in Los Angeles, where the actress went without shoes for the day to bring global awareness to children's health and education needs.

celebrated at the Breast Cancer Foundation's 2014 Hot Pink Party at the Waldorf Astoria Hotel in New York City. Hurley acted as host for the evening, while Bareilles and John performed. "I know so many people personally who have been affected by breast cancer, which makes it such a moving cause to me," Hurley tells InStyle.com.

also came out to support a great cause at the Hot Pink Party, which raised over $5 million in funds for the Breast Cancer Research Foundation.

attended the Pharrell Williams UNIQLO "i am OTHER" Collection Launch at UNIQLO's Global Flagship Store in New York City. "When it comes to style, just do what you want to do, that’s what it’s about—it’s about being comfortable," Williams says.

premiered their new movie Neighbors at Regency Village Theatre in Westwood, California. The comedy also stars Rose Byrne and Dave Franco, and hits theaters May 9, 2014.

looked stylish at the 2014 National Dance Institute Annual Gala at Best Buy Theater in New York City, which raised funds for the NDI’s award-winning arts education programs for New York City public school children in under-resourced neighborhoods.

celebrated at the premiere of their film Begin Again at the 2014 Tribeca Film Festival Closing Night Gala hosted by Chanel. "He didn’t need any acting tips from me, he’s just a sort of natural entertainer and he’s a born actor," Knightley tell InStyle about Levine’s first feature film debut. "I’ve never met anybody that has the amount of energy he has at work, he bounces off the walls and you just sort of watch him and go 'wow!'"

were all smiles at Lanvin's 3rd Annual Living Beauty Fundraiser in Beverly Hills, California. "Tonight was so beautiful," Roberts tells InStyle. "I think it's so amazing to use fashion to support a great cause that makes women feel amazing about themselves."

feted the designer at a party to celebrate his fall 2014 collection at Decades in Beverly Hills. "I've known Christian for years now, I love everything about him, and he always seems to know what works best on my body," Suvari tells InStyle exclusively. "I think he's very smart with his choices each season, and he really knows what's flattering on women."

were a stylish group at the Variety Power Of Women: New York event held at Cipriani 42nd Street in New York City.

attended the Jonsson Cancer Center Foundation's 19th Annual "A Taste For A Cure" in Beverly Hills, California, where the duo not only supported a great cause, but also performed.

came out for a good cause at an event for Worldwide Orphans in New York City, where Garfield spoke to the crowd about the organization's goal to transform the lives of orphaned children around the world by helping them become healthy, independent, productive members of their communities.

walked the red carpet in a floral ensemble at the Radio Disney Music Awards in Los Angeles, where she presented an award. Hale will release her own debut album, Road Between, on June 3, 2014.

posed backstage at Hedwig and The Angry Inch on Broadway at The Belasco Theater in New York City. Perry came out to support Patrick Harris, who stars in the show.