This season, the 6-foot-8, 205-pound forward averaged 19.9 points, 10.2 rebounds, and 2.7 blocks in sparking the squad to a 22-5 mark.
"He was the heart and soul of our team," Friends' Central coach Jason Polykoff said. "I think he had a tremendous year."
For another stellar showing, Jefferson is The Inquirer's Southeastern Pennsylvania boys' basketball player of the year for the second straight season.
"It's been a wonderful experience for me at Friends' Central," Jefferson said. "I'm going to miss Coach Polykoff, my teammates, the practices. It makes leaving bittersweet."
On Wednesday night at Chicago's United Center, the 18-year-old, who honed his skills on hard courts in West and Southwest Philly, participated in the 35th annual McDonald's All-American Game.
In 14 minutes, Jefferson shot 4 for 10 from the field (0 for 1 on threes) en route to eight points, and grabbed three rebounds. His East squad bowed to Shabazz Muhammad (21 points) and the West, 106-102.
"It was a lot of fun playing with all those guys," he said. "It was a fast-paced game, with both teams flying up and down the court. I expected that. That's what usually happens in all-star games."
In his career at Friends' Central, Jefferson, productive in the paint and in transition, totaled 1,569 points, 839 rebounds, and 189 blocks.
His second all-star appearance will come Friday night in the Derby Festival Classic in Louisville, Ky. Polykoff will co-coach Jefferson's squad with Danny Henderson, of Marcus High (Texas).
The blue-chip recruit has yet to finalize his college destination. He says North Carolina State, Duke, Kentucky, Villanova, and Ohio State remain in the running.
"I still think I'm going to need a week or two to make that decision," he said Thursday.
And can he see the day when he's playing in the professional ranks?
"I've got a lot to work on," he said. "I have to get bigger and stronger. I want to develop as a person, too. It's all a work in progress."
Contact Rick O'Brien at email@example.com or @ozoneinq on Twitter.