The average Brit is still in touch with five friends from their school days - and over a third remain close to their very first best pal.
The study of 2,000 UK adults found the bonds formed in primary school can last a lifetime - with 35 per cent revealing their first best mate shaped who they are today.
On average UK adults met their best pal from childhood aged seven - going on 38 adventures, overcoming 14 fall-outs and experiencing 13 life-changing events together.
However, respondents typically drifted apart from their first best mate age 15 years old - with moving house and going to different schools the most common reasons why.
While a fifth admit their relationship with their childhood friend is now limited to Facebook and other social media.
Commissioned by kids TV show, Kate & Mim-Mim, airing on CBeebies every weekday at 8.50am, the research also found half of those no longer close to their first best friend wish they still knew them.
Kirstie Brockett, brand manager for Kate & Mim-Mim, said: “Friendships formed in childhood can have a huge effect on our lives and it’s great to see so many of these are lasting well into adulthood.
“Many of us drift apart from friends made during our formative years however the research suggests that bond has played a significant part in who we are today.
“For many of us, the moments experienced together in that time will stay with us forever and hopefully be looked back upon with great fondness.”
Fifty-two per cent of people met their best friend at primary school - while almost a quarter met because they were neighbours or lived close-by to each other.
Among the adventures most commonly shared with best friends are bike rides, building dens and exploring the woods.
Other precious shared-adventures with pals included searching for ghosts, being chased by farmers and sleeping under the stars.
Almost a fifth of respondents are still tight with an entire group of friends they first met in nursery or primary school.
Respondents typically had six close friends at nursery, seven at primary school, eight at secondary school and eight between the ages of 16 and 18.
While 15 per cent of Brits said they didn’t have a best pal during their years as a child and one in 10 people had an imaginary friend when they were younger.
Respondents’ imaginary friends included a frog, a dragon called Peter, a goblin - and a giant teddy bear named George.
On average UK adults have four close friends and over half currently have someone they consider to be a best friend.
Respondents also revealed some of their favourite toys from early childhood - with some of the more peculiar ones including a hot water bottle and a camera case.
Parenting Consultant and author, Eileen Hayes MBE, said “We are born as social beings - even as babies, right from the start, we are social and want to communicate.
“Small children are also intensely interested in other small children when they start to meet them - almost leaping out of the push-chair in their excitement - and they love to play and socialise.
“We see from the Childhood Friends survey results, the importance of these early friendships and how they shape the adults we become - even if we are not actively in-touch with them.
“So it’s important for parents to do everything they can to encourage positive friendships for our children.”