Wilbur C. Riley Director of Athletics Bill Stiles announced the following new coaching appointments for the upcoming 2026-27 school year.  

"We are thrilled to announce the appointment of three new head coaches for the upcoming school year, each of whom is already a valued member of our community,” said Stiles. “These appointments reflect the exceptional talent, dedication, and leadership we are fortunate to have at Hill, and we are excited to see each of them continue to shape the experience of our students in these expanded new roles." 

Bart Mestelle | Girls’ Indoor and Outdoor Track and Field

The Hill School is proud to announce the elevation of Bart Mestelle to Head Girls' Track and Field Coach. Coach Mestelle, who served as an assistant coach at Hill last season, brings a decorated competitive background and nearly a decade of coaching success spanning the collegiate, club, and high school levels.   
 
“The addition of Coach Bart Mestelle in the past year has helped both the girls’ and boys’ track and field teams to reach new levels,” said Bill Yinger, Frank E. Richardson '20 Coach of Boys' Track and Field. “The appointment of Coach Mestelle to the ranks of Head Girls’ Track and Field Coach for the coming seasons deepens the effects that he has had on the program as that team rises through the ranks of both the MAPL and PAISAA leagues. 

"Coach Mestelle has quickly established himself as a master technician, earning the respect of his coaching peers as he deftly leads a group of talented individuals to accomplish goals beyond what they personally thought possible. Moreover, his kind manner and patient demeanor have allowed some of our most developmental athletes to also thrive and to prove their own goals to be attainable.  On a personal note, I look forward to further collaboration with Coach Mestelle in the coming years as he continues to push for nothing but excellence in our track and field athletes here at Hill and welcome his addition to this leadership position.” 
 
A standout combined-events athlete at the University of Wisconsin–Eau Claire, Coach Mestelle earned NCAA All-American honors twice in the heptathlon and decathlon. As a team captain, he helped lead the Blugolds to two runner-up team finishes at the NCAA Championships. He still holds the UW–Eau Claire school record in the pentathlon and previously held the program's heptathlon and decathlon records.  

Coach Mestelle began his coaching career at Emporia State University (2013–2015) as a graduate assistant, working with the high jump and combined events groups. During that span, his athletes earned five NCAA First Team All-American honors, with five high jumpers and six combined-event athletes reaching NCAA Championship qualifying marks.  

At William Jewell College (2015–2017), he served as an assistant coach before being elevated to head coach, overseeing the sprints, jumps, hurdles, and combined events and helping host the GLVC Conference Championship. Under his direction, athletes rewrote the record books, setting new indoor school marks in the men's 200m and 60m hurdles and the women's 60m, 200m, 60m hurdles, high jump, and pentathlon, plus outdoor records in the men's 100m, 200m, 110m hurdles, and 400m hurdles and the women's long jump, 200m, 100m hurdles, 400m hurdles, and pentathlon.  

With the Team Idaho Track Club (2018–2022), he directed sprint training and coached the horizontal jumps. As sprints and hurdles coach at Borah High School (2019–2022), Coach Mestelle helped guide current professional runner Nathan Green to numerous state titles, helped four athletes qualify for the state meet in the hurdles, led the boys 4x400m relay to a state title, and led the boys to a runner-up finish in the 400m. As the sprints and jumps coach at Centennial High School (2019), he coached four athletes to state championship qualifying marks in the long and triple jump.  

Coach Mestelle holds USATF Level 1 and USA Weightlifting Level 1 certifications and is a Certified Strength and Conditioning Specialist (CSCS). He holds a bachelor's degree in education and chemistry and an M.S. in exercise sciences.  

Joe Millman | Director of Squash

 The Hill School has selected Joe Millman as its new Director of Squash, bringing more than 20 years of elite coaching experience, international playing credentials, and a proven record of developing student-athletes for collegiate success to the program. Coach Millman worked with the Hill Squash program last season as an adjunct coach.  

“The addition of Coach Millman elevates our program to the next level,” said Josh Schoeifled, Hill’s Director of Racquet Sports. “Having someone with Coach Millman’s talent and expertise will be an invaluable asset to our players. They will benefit from year-round coaching that will help them continue to develop their skills, and we will be better positioned to attract highly rated players. I am overjoyed by this addition to the Hill community.” 

Originally from Norfolk, England, Coach Millman began playing squash at age 15 and moved to New York at 17 to pursue elite junior competition and launch his coaching career. He later competed professionally on the PSA World Tour, achieving a career-high world ranking of #168 and a US Squash rating of 6.59. 

Since 2010, Coach Millman has built a distinguished coaching career in the Philadelphia area. Most recently, he served as Squash Professional at The Cynwyd Club from 2021–2026, where he delivered high-performance coaching for junior and adult athletes, developed individualized training plans for nationally ranked juniors, and supported collegiate recruitment. 

Prior to Cynwyd, Coach Millman was Senior Squash Director at SquashSmarts in Philadelphia from 2017 to 2021. Under his leadership, program enrollment grew from 60 to more than 150 students. He oversaw coaching staff, curriculum development, and athlete progression while building pathways for junior competitive success and expanding community outreach programming. From 2010 to 2017, he was Squash Professional/Assistant Manager at Berwyn Squash Club, developing numerous athletes who advanced to regional and national competition. 

At The Hill School, Millman will focus on core areas including athlete development, high-performance coaching, college recruitment, program management, tournament operations, and community engagement. 

Coleman Weibley | Director of Swimming and Diving & Amy Agnew P'11 | Head Coach of Swimming and Diving

The Hill School is excited to announce our succession plan in leadership and coaching in the swimming and diving program with the appointment of Mr. Coleman Weibley as Director of Swimming and Diving and Mrs. Amy Agnew P'11 as Head Coach. Coaches Agnew and Weibley will join Head Diving Coach Jen Edelman, and Assistant Coaches Carbery Campbell, Chris Schiavone, and Sara Vukas to form a student-centered team whose shared commitment, communication, and experience will elevate the swimming and diving experience for our students.   

Coach Weibley arrived at Hill in 2024 and serves as the Dean of Students. He was appointed the Director of Swimming and Diving in 2026. In this new role, he is responsible for strategy and logistics around team operations, including scheduling, travel, and meeting management. He serves as the primary liaison to the athletics and School administration and supports admission, advancement, parent, and alumni relations functions. Coach Weibley has many years of high school, club, and college coaching experience, including The University of Tennessee and Florida State University, where he oversaw daily operations, team travel, meet logistics, and recruiting. Most recently, Mr. Weibley was an assistant coach at Mercersburg Academy where he helped guide the program to multiple Easterns championships. He also serves as the Meet Director of the MAPL Championships.  

Coach Agnew returns to the head coach position after leading the Hill Swimming & Diving program from 2016-2020 and serving as an assistant coach from 2020-2025. Under her leadership as head coach, Hill recorded five top-10 finishes at Easterns and swept Lawrenceville in 2018 and 2019. Now in her 10th year at Hill, Coach Agnew teaches in the English department and is the Director of Aquatics. Including her tenure at Hill, she has more than 26 years of teaching and coaching experience at Montgomery County Community College, Chestnut Hill College, TOPS swimming, and various USA Club teams. For many summers, she and her husband, Mark, traded head and assistant coach roles at North End Swim Club and Bellewood Country Club. Now, they swim in Lake Champlain during their summers in Vermont!