Rob Holding has joined Arsenal from Bolton Wanderers for an undisclosed fee.
The England U21 international defender joined Bolton as an eight-year-old and, after progressing through the youth ranks, broke into the first team last season.
He made his debut against Burton Albion in August 2015 before going on to become a virtual ever-present throughout the second half of the campaign.
The 20-year-old scored one goal in 30 appearances before being named as the club's player of the year at the end of a season which saw them relegated to League One.
His performances were rewarded with a call-up to Gareth Southgate's U21s and he made two appearances in helping England win the Toulon Tournament in France over the summer.
In a brief statement, Bolton said; "Everyone at Wanderers would like to thank Rob for his efforts during his time with the club, and wish him well in his future career."