Robert "Bobby" Costello started riding in as a child in Massachusetts, competing at local shows and fox-hunting with the Myopia Hounds. He found the sport of eventing and worked his way through the ranks as a professional, ultimately competing at the highest levels in the sport of eventing.

Costello became an upper-level staple for the program, representing the U.S. Eventing Team at the 2000 Sydney Olympic Games in Sydney Australia, taking eighth individually with Chevalier. The pair also secured top results at Bughley CCI5*-L and the Rolex Kentucky Three-Day Event. Costello finished seventh individually at the 2003 Pan American Games with Dalliance, before turning towards coaching and eventually stepping away from riding full-time in 2010 and focusing solely on coaching and training. 

Since he joined the program in 2022, Costello has helped several senior teams produce significant results at major international competitions and championships including a team silver at the 2022 FEI Eventing World Championships in Pratoni del Vivaro, Italy, and a team silver at the 2023 Pan American Games in Santiago, Chile. Under Costello's tutelage, the team has also secured two-consecutive second-place finishes in the CCIO4*-S at CHIO Aachen in 2023 and 2024. 

James Alliston is a dedicated eventing athlete and trainer, known for his commitment to developing both horses and riders. He grew up in Gloucestershire, England, where he was involved in Pony Club, honing his skills in various disciplines. After taking a gap year from university to immerse himself in the horse industry, Alliston apprenticed for U.S. Eventing athlete Bruce Davidson, Sr. This experience influenced his training philosophy of emphasizing the importance of producing fit, competitive horses. 
 
In early 2022, Alliston changed his nationality from British to American after residing in the U.S. for over 15 years. Soon after, he was selected to represent the U.S. Eventing Team at the FEI Eventing Nations Cup in Boekelo, Netherlands. He and Alliston Equestrian’s 8-year-old gelding, Nemesis, served as pathfinders for the team. 
 

Over the years Alliston has continued to achieve success at the CCI4* and CCI5* levels. In 2023, he once more represented the U.S. Eventing Team at Boekelo, this time riding Ric Plummer and Alliston Equestrian’s mare, Karma, where they finished on their dressage score of 35.9, leading the U.S. Eventing Team to a fourth-place finish. Alliston and Karma were named to the Defender U.S. Eventing Team for CHIO Aachen in 2024. The pair not only produced a double clear show jumping round, but assumed the role as pathfinders and crossed through the timers with just 2.4 time penalties to finalize their outing on a score of 38.4, finishing ninth overall individually and as the highest-placed team combination in the 2024 SAP-Cup CCIO4*-S. 
 
James owns and operates Alliston Equestrian and East Bay Riding Academy in Castro Valley, Calif., where he trains alongside his wife Helen. 

Jennie Brannigan is a successful alumna of the USEA Young Riders Program, having won team and individual gold at the 2008 NAYC for eventing with her own KWPN gelding, Cooper. She completed her first CCI5*-L in 2015 at the Rolex Kentucky Three-Day Event with Nina Gardner’s Cambalda. In 2021, Brannigan finished in fourth place overall at the Maryland 5 Star CCI5* with the Stella Artois Syndicate’s Stella Artois. 

 
Brannigan has represented the U.S. Eventing Team on multiple occasions, including being named to the CCIO3* (now CCIO4*-NC-L) team at Boekelo four times from 2012-2023. She has competed at 12 CCI5*-L events and participated in five Nation’s Cups in total for the U.S. Eventing Team. 

Recent top results for Brannigan include strong performances at the Defender Burghley CCI5*-L, earning a top 12 finish and the “Best First Timer” award with Dr. Tim and Nina Gardner’s FE Lifestyle. In early 2025, Brannigan claimed victory in the CCI4*-S at the Setter Run Farm’s Carolina International with FE Lifestyle, marking a significant addition to her list of accomplishments. 

Phillip Dutton began riding horses on his family farm while growing up in Australia. He moved to the U.S. in 1991 to prepare for the Atlanta 1996 Olympic Games and continued representing his native country until 2006, when he became a U.S. citizen. Dutton has been a mainstay on U.S. teams ever since.

Dutton has competed in every Olympic Games since 1996, winning team gold with Australia in 1996 and 2000, and as a member of the U.S. team in 2008, 2012, 2016, and 2020. He won individual bronze with Mighty Nice at the 2016 Olympics in Rio de Janeiro. He has competed in seven FEI World Equestrian Games, representing the U.S. for the first time in 2006. He won team gold and individual silver at the 2007 Pan American Games with Truluck and team gold at the 2015 Pan American Games with Fernhill Fugitive.

Dutton has been the top-finishing American at the Kentucky Three-Day Event several times, winning the USET Foundation Pinnacle Cup in 2017 with Mr. Medicott, 2015 with Fernhill Cubalawn, 2010 with Woodburn, and 2007 and 2008 with Connaught. In 2008, he was also the overall winner of the event.

Recently, Dutton and Z were fourth at the 2022 Maryland 5 Star CCI5*-L and fifth at the 2023 Land Rover Kentucky Three-Day Event presented by MARS Equestrian^TM CCI5*-L.

Dutton resides in Pennsylvania with his wife Evie, twin daughters, Mary and Olivia, and stepdaughter Lee Lee.

With 47 FEI career starts at the age of 21, Cassie Sanger is one of the country’s top young eventers. Sanger started riding at the age of eight after being encouraged by her grandmother. She leased her first horse, Danger Mouse, from Caroline Pamukcu in 2021 before adding Redfield Fyre and Fernhill Zoro to her impressive string of horses.  

Sanger’s international success took off in 2023 when she and her own Fernhill Zoro placed top 5 in the TerraNova CCI4*-S in Myakka City, Fla. That same year, she was selected to the 2023 Eventing 25 Emerging Athlete Program and later selected for the U.S. Eventing European Development Tour where she made her Nations Cup debut at the FEI Eventing Nations Cup Poland CCIO4*-NC-S, helping the U.S. Eventing Team secure a silver medal finish. Sanger later added another podium finish at Bromont in the CCIU253*-S with Redfield Fyre and delivered the team’s top dressage score at the FEI Eventing Nations Cup Netherland CCIO4*-NC-L with Fernhill Zoro.

In 2024, Sanger continued to make her mark, earning a spot on the Eventing Development 25 Program List. She and Fernhill Zoro were a part of the winning team at the USEF Futures Team Challenge at Carolina International and secured top 5 finishes with both Redfield Fyre and Fernhill Zoro at the Defender Bramham International CCIU254*-L. She and Fernhill Zoro were selected for the 2024 U.S. Eventing European Development Tour and the FEI Eventing Nations Cup Great Britain CCIO4*-NC-S. She returned to Bromont for another top finish, this time with Fernhill Zoro, and competed as the youngest athlete in the field on the U.S. Eventing Team at the FEI Nations Cup Netherlands CCIO4*-NC-L with Redfield Fyre.  

Entering 2025, Sanger was named to the Eventing Development 25 Program and kicked off the season with a win aboard MT Luxaan at the Carolina International CCI2*-S.