Children from the primary school where a gunman killed 26 people last month are to start the new term at what police say is the US's "safest school".
Sandy Hook Elementary School in Newtown has been closed since Adam Lanza killed 20 pupils and six staff on 14 December.
Chalk Hill, a disused middle school in nearby Monroe, has been renovated by an 80-strong team and renamed Sandy Hook, the BBC reports.
The use of furniture from Sandy Hook had turned it into "a very cheerful elementary school", officials said.
Extra security measures were being taken at the new school, such as stopping every vehicle that entered the school grounds, said Monroe Police Department's Lieutenant Keith White.
"I think right now it has to be the safest school in America," he said.
Acting principal Donna Page, who has replaced the slain school head Dawn Hochsprung, wrote to parents of pupils that the school was "safe, secure and fully operational".
Parents would be allowed to stay in the school during class-time on Thursday to reassure their children, she added.
"That being said, we encourage students to take the bus to school in order to help them return to familiar routines as soon as possible," she wrote.
Lanza, 20, carried out the attack after killing his mother, the legal owner of the weapons, which included a semi-automatic rifle.
He later shot himself, and was reportedly buried over the weekend after his father, a tax executive, retrieved his body from the authorities last week.
The shooting revived fierce debate over America's controversial gun control laws, with some pro-gun politicians saying it had prompted them to change their views on the issue.
The Obama administration has indicated it will look for ways to tighten gun laws, and President Barack Obama has given his deputy, Joe Biden, the task of establishing a set of "concrete proposals" within weeks.
Mr Obama has said he would support re-instating an assault weapons ban that lapsed in 2004.
The White House has also suggested the President would back other gun control measures on high-capacity ammunition clips as well as closing loopholes that allow people to buy guns without background checks.
The National Rifle Association, a powerful US lobbying group, argues against more regulation, saying teachers in schools should be armed in order to better defend students if a shooting occurs.