The 23-year-old forward joined the Saints in the summer of 2011 and has so far played 18 times in the club's first team, including in the 2012 LV= Cup final and Aviva Premiership Rugby semi-final.
Craig is comfortable at both lock and in the back row, and although injury has cruelly prevented him from adding to his tally of appearances so far in 2012/13 he says he is determined to get fully fit and contributing to the black, green and gold cause as soon as possible.
"It has been a bit frustrating for me in terms of injuries this year, but I'm glad that the coaches have seen past that and seen my potential for the future," he commented. "Being a part of the Saints has been a great experience, and hopefully I can get back into the matchday 23 when I get back to fitness.
"Settling into the club has been a steady transition and I feel very much at home here now. It's a great set of lads, a good crowd, good coaches, and you can't say more than that.
"Looking forward I know I need to break into the first team. It's going to be hard; we've got quality players across the back five forwards, including a lot of England internationals, but I'm determined to keep improving as much as I can."
Director of rugby Jim Mallinder says that Craig is a player who can provide a substantial contribution to the squad in the future.
"James is a talented player who has shown already that he has the ability to compete at the top end of the Aviva Premiership Rugby table," he said. "He can play both in the second row and on the flank, and you need that kind of positional flexibility in the squad.