Dozens of school pupils running their own companies for a year as part of the Young Enterprise programme set up stalls in the intu Watford Centre.
From their trade fair stalls the pupils sold products to customers on Saturday and Sunday, and competed for various awards.
The Young Enterprise scheme matches up student entrepreneurs with volunteer business experts who help them market and sell their products.
Magnacarda from the Merchant Taylors School won Best Overall Company on Saturday and Vivid Fuller from Rickmansworth School clinched the title on Sunday.
Jinja from The Royal Masonic School for Girls in Rickmansworth won Best Stand.
Katy Burke, Young Enterprise manager for Watford, said: "The event exceeded the expectations of the intu management, our judges, and the Young Enterprise volunteers.
"The level of professionalism, innovation and enthusiasm among our students was outstanding."
Taking part in the intu event this year were Watford Grammar School for Girls, Watford Grammar School for Boys, Merchant Taylors, Rickmansworth, St Helens, The Royal Masonic and St Margret’s, Longdean School, JFK School and Berkhamsted School. St Albans Loreto College, Sir John Lawes and St Columba’s College.