Ella Pallister was a student at Thomas Hardye School in Dorchester.
In a statement the school said: "We are devastated by the news of the tragic and sudden death of Ella Pallister.
"She was studying in Year 13 and she was a popular, bubbly, hard- working and caring student.
"Her closest friends are in shock, but the whole sixth form and school community are grieving for her loss.
"Our thoughts and condolences are with her family at this very sad time."
@ellapallister going to be so weird with out you being around now! You were such a good cousin and I'm so glad I've met you! I love you x x
From @XCharlie98 on Twitter:@ellapallister I love you so much, going to be so hard without you, miss you so much. Rest in peace beautiful, best fried I could ever have!
From @GabyMcNamee98 on Twitter:feel so sorry for the family of the Ella Pallister, such a tragic accident RIP
From @kathleen_clover on Twitter:
Ella Pallister's parents have paid tribute to her and her love of horse riding saying "Ella was our shining star.
"All she has ever wanted was to ride her ponies and win her competitions in the fastest time possible".
The 17 year old died after she fell from a horse in Dorset on Sunday.
Ella Pallister from Portesham in Dorset was competing near Dorchester on Sunday when she fell from her horse. The seventeen year old was flown to Southampton General Hospital, where she died.
British Showjumping have confirmed that 17 year old Ella Pallister, from Dorset died yesterday as a result of an injury sustained whilst competing at a British Showjumping affiliated show at Kingston Maurward in Dorset on Sunday.
Ella fell from her horse in the warm-up arena and was transferred to Dorchester Hospital prior to being taken by Air Ambulance to Southampton Hospital.Both British Showjumping and Kingston Maurward said on their website that they extended their condolences to the family during this difficult time.
A post office worker is painting a post box in Alton gold after Peter Charles won a gold medal as part of Team GB's show jumping squad.
The Royal Mail is releasing a special set of stamps to commemorate the gold medal won by Team GB's show jumping squad.
Peter Charles from Alton in Hampshire was one of the men who won Team GB's first gold show jumping medal in 60 years.
The first British showjumping team to win Gold medals for sixty years celebrate their achievement. From left to right they are Nick Skelton, Ben Maher, Scott Brash and Peter Charles who is from Alton in Hampshire.
A showjumper from Hampshire raised his riding helmet with delight today as he secured the British showjumping team's victory at the Olympic Games.
Peter Charles, who is based in Alton, was one of the team of four who won the British showjumping team's first gold medal in sixty years.
People watching the victory roared and stamped their feet as the team - Peter Charles, Nick Skelton, Ben Maher and Scott Brash - took the title in what has been described as the equivalent an equestrian penalty shoot-out.
The last time a British showjumping team won an Olympic gold medal was in Helsinki in Finland in 1952.
Peter Charles from Alton has won a Gold medal in today's Olympics 'team showjumping'.
... More to follow